With the Bad Batch show, people have begun to ask why the Empire stopped using clone troopers and transitioned to using recruited soldiers. People cite the better performance of clone troopers as being the entire reason for the Empire's apparent stupidity on the matter and that if the Empire was still using clones, they would have beaten the rebels.

I am going to make a controversial statement in that a recruited army is more efficient than a clone army, even if the clone army performs better on an individual basis. So why such a bold statement? In what way is a stormtrooper better than a clone trooper and why would the Empire downgrade its troops? The answer is more complicated than simply "muh Tarkin doctrine" and I will answer it point by point.

1.) Cost. Clones are expensive, massively expensive. The reason they are expensive is because the Empire and Republic had to pay Kamino for everything, all while Kamino made a profit on them. Profit motivations aside, the cost of a clone does not come from their equipment, but their upbringing. Compare the cost to the Empire in training and equipping one soldier to one clone trooper. For a recruited soldier, all they have to worry about is the training and equipping of that soldier for his tenure. But the clone? The Empire (and Republic) have to foot the bill to raise them from birth. 10 years of education, food, housing, clothing, entertainment, location of housing. The training and outfitting of this trooper is relatively minimal compared to the cost of living. How many more troops could you train and equip if you didn't have to worry about the cost of upbringing? The answer would be a lot higher.

2.) Training. One thing people say that clones are better at is fighting and this is true. Clone troopers are better (onscreen evidence shows that both stormtroopers and clone troopers are pretty similar in performance against main characters) than any other soldier in the galaxy. There is an issue in that with so much training you eventually reach a point of diminishing returns. There is only so much training you can give a normal non-augmented human before the training stops improving their fighting ability. Clones have reached that limit and there isn't really much you can do aside from massively investing in their equipment to improve them. On the other hand, recruited soldiers (especially volunteers) will get good training to be respectable soldiers and that is the goal of the Empire. Why put so much effort into training the best possible troops if the difference at that level isn't very big? Then coupled with the cost of a clone vs a recruit, the recruit begins to see a much better return on investment. You can field more volunteers of reasonable quality than clone troopers for the same cost.

3.) Fighting the Last War. The clone wars were massive and while the Republic had the edge in the naval theatre, they were hilariously outnumbered on the ground. Of course 1 clone was worth over a dozen droids, but there were so many more droids that it didn't even matter. Why is this relevant? Well after the clone wars, the high ranking officers of the Imperial military are thinking: "Damn, if we had more troops we could have contested the Separatists on more fronts and had a more active force, rather than a reactive force". The Empire prepared in fighting another war like the clone wars, with massive battlefleets and grand armies on the ground (which you can see reflected with their large and diverse fleet of star destroyers, cruisers, corvettes, and TIE's). The best way to do that is with a massive army and with the aforementioned cost issue, a clone army simply cannot be large enough to fight that kind of war. A large, reasonably well trained army will beat an elite army because they can defeat them in detail. That is, the larger army will easily be able to isolate small parts of the elite army and beat them one at a time, or all at once with many armies. That is exactly what happened during the clone wars and that is what the Empire can do with a recruited army. The Empire's entire military is better suited to fighting something like the Imperium of Man than the Rebel Alliance because they are trying to use a sledgehammer to kill a swarm of mosquitos. So with a much lower cost per trooper that is still good enough, the Empire can easily put its attention in many more places.

4.) Mass Mobilization. If need be, a gargantuan army can be raised in 6 months to a year with recruits. We have seen this happen many times throughout history and it has turned the fate of nations. Rome quickly raised new legions after their terrible defeat at Cannae and eventually won the war despite losing over a fifth of its entire able-bodied male population over 17. The Soviet Union quickly raised an army of millions following Barbarossa, again winning the war like the Romans. The USA and UK mobilized millions of troops in their militaries, many being volunteers as soon as the war started. However, that could not be done with a clone army. If you need a massive troop surge, you need to give Kamino a 10-years notice, which isn't exactly convenient when you need an army now. Since the Empire was thinking the next war would be like the clone wars, they thought that having a conventional military would be more important, so that they could expand their military under short notice, rather than panic like they did during the clone wars. It is important to remember that the Republic almost went to war with no army, so the Empire learned its lesson and made sure not to be defenseless. A second benefit to this model is that it better saves the Empire from a surprise attack which could wipe out a huge portion of a cloned army.

5.) An Uncertain Source. Kamino is the only planet which produces clones on the scale needed to supply the Empire. A single decapitation strike would completely stop the production and training of clones and this nearly happened during the clone wars. What would the Empire or Republic do if they suddenly ran out of clones? By using recruited troops, you can train them anywhere and base them anywhere. You aren't limited to using Kamino for their upbringing and you don't have to worry about losing the source of your entire army from 1 planet. This leads into another point, if you want to produce more clones, you have to go to the Kaminoans and build more cities to house more clones and train them and that costs a lot of money and Kamino gets a say in how its done, how much it costs, and they control the source. That is an unmentioned point. The Empire has to negotiate with Kamino on clone production, giving Kamino disproportionate levels of power, making it quasi-independent. What leverage does the Empire have over them? Other than payment, not much really. The Kaminoans are the ones with the clones and what if Kamino decides to rebel? There goes your army. What if the Kaminoans put inhibitor chips making the clones entirely loyal to Kamino (which they can do and already did at the behest of Sidious against the Jedi)? Kamino hasn't been shown to be very upfront and they are kind of scummy (see the genocide against their own people). This is a very dangerous line and it gives Kamino an uncomfortable amount of control. It'd be like if a government today got all of its troops from 1 city, but that city is already quasi-independent and you pay them for those troops. With recruited troops, you don't have to worry about this massive security issue. Sure the Empire could glass Kamino with a single star destroyer, but then they have no more troop source.

6.) Societal Tension. When a stormtrooper is finished with their service, they leave the military and go to a civilian job. They get a nice pension from the Empire and can easily reintegrate with society, which will be easy because they have lived as civilians for most of their lives. Clones will retire at some point too. They will be too old to fight, but still young enough to work. However, with a clone, all they know is what Kamino taught them. They cannot interact with normal people because they never have. Millions of clones will be just wandering around looking for jobs and as they have never had normal lives, they will not be able to smoothly integrate with society. They will likely form into their own clone communities and as they are shunned by society they will become disgruntled. An angry army of former soldiers is a very dangerous thing, as seen many times throughout history. Actual rebellions have started from these soldiers. These rebellions will be put down by other clone soldiers who will likely hold sympathies for these older clones and they may even take their side. To avoid this, the Empire has to foot the bill on a clone's retirement. With a recruited army all the Empire has to do is give them their pension and the person will be fine, as they are just getting back to civilian life and the adjustment won't be nearly as bad as a clone who only knows war.

Summary: Replacing clones with stormtroopers isn't a terrible decision because of the lower cost, higher efficiency for their cost, similar performance. A stormtrooper army can be raised under short notice, but also the lessons of the clone war taught the Empire that a large military is needed to win a similar conflict in the future. Furthermore, Kamino is a shady source of troops and poses a massive security concern. Finally retired clones cannot be reintegrated into society because they have never been civilians, whereas stormtroopers can easily transition back into civilian life with ease.