So I'm clearly missing something about staves, because they're apparently the spellcaster equivalent of fundamental runes, but they just seem...not good?

You get charges to cast the spell equal to your highest level of spells, it takes a number of charges equal to the spell's level to cast, and you can only cast a spell from the staff if you already know the spell anyways. So it basically gives you a single extra spell slot of your highest level spell slot that you can only use for a single spell?

And then the alternate version for Spontaneous casters, you can expend a spell slot in order to only need a single charge to cast the spell...but how is that any better than just using the spell slot to cast the same spell and not worrying about the staff's charges at all? It just seems like a clunky accessory to not actually do anything different.

It's incredibly possible that I'm misreading something somewhere, but these just seem like a waste to me.

EDIT: I realize that there is the phrase " You can Cast a Spell from a staff only if you have that spell on your spell list " in the rules, but "your spell list" is not the same as "your spellcasting tradition", and I feel like PF2 as a system made a pretty strong effort to separate the terms.