Disclaimer: This is my personal opinion, and though I believe many Mech players share it, I don't want to go so far as to actually claim that they do.

Going into LotV with the addition of the Ravager and the Disruptor, Blizzard realized the Siege Tank would need some kind of buff. Rather than give it a straight damage/health buff, Blizzard came up with the idea of the Tankivac.

It was brilliant. It was a massive buff to the Tank that also added some really cool micro potential and allowing it to go toe-to-toe with the new units, while also inventing a new, exciting way to play Marine/Tank that was viable in all matchups. I really like the Tankivac.

So, you may ask, what is the problem with the Tankivac? The answer, is that there really isn't one. Sure, some people may say that it makes Doomdrops easier, but at the same time it also makes them easier to defend. And engagements may come down to who drops the Tankivacs first, but at the same time it makes retreating from such bad engagements easy.

The real problem, lies only indirectly with the Tankivac in the fact that it does not allow the Tank to be buffed in any other way, and not everyone want to play the new Marine/Tank style every game.

If you are going full Mech, you don't have enough gas to both build enough Medivacs to move your army, and build enough Vikings/Libs/Ravens to keep air control. Therefore, you don't see the Tankivac with full Mech, which means, when going full Mech, you effectively have the same old, unbuffed HOTS Siege Tank.

Siege Tanks, by themselves, are really weak. You need to turtle hard with turrets until you have a ton of them before you can push out. If they were buffed enough to actually make them cost efficient, you would be able to push sooner, and you would need fewer of them, allowing you to spend more gas on Vikings/Libs, effectively eliminating Mechs AA issues as well. But if you were to buff them like this, Tankivac would become too strong, making the Siege Tank literally not have a weakness. But as things stand Right now, Tankivac, and fast, opportunistic, gorilla Bio styles are just superior to Mech.

The Tankivac has indirectly put Mech in a bad spot, not allowing them to change the Tank in the way it needs to be changed, and it is unfair for the Bio players to ask us to lose OUR style so they can keep theirs. On the flip side, it is also extremely unfair for us Mech players to ask Blizzard to effectively remove the Tankivac play style that many of come to love just to make our own style viable again.

There is also the argument that it has "changed the identity" of the Siege Tank. I don't know how much I read into that argument but it is definitely and issue for some.

Some middle ground needs to be achieved. What that is, I don't know. Perhaps some kind of "Heavy Weapons" upgrade for the Tank that would increase their damage, but make it so they cannot be picked up in Siege Mode again. There are many great options that could be, and have been discussed.

To end, I am not in favor of removing the Tankivac because so many have come to love it, but something else needs to be done for the Tank. We need to meet in the middle!

Edit:a word.