Miss 4e D&D

[Kurald Galain]

In most scenarios where these don't apply, Power Attack is significantly weaker than just attacking twice.

But that's a problem. You spend resources (like a feat) on gaining a new ability (like Power Attack) and then it turns out that this ability is actually weaker than what you could do without the feat.
And it's not just this particular feat, either. Effectively, that means that the players spend a lot of effort (and the books, a lot of page count) on options that don't actually matter.

Basically, the system is designed to limit vertical progression (how strong can you make this one tool), while providing a lot of horizontal progression (how many tools are you competent with).

But PF2 clearly gives you much less horizontal progression than in 3E or PF1 or 4E. Compared to 5E it's debatable; I suppose PF2 is on-par with 5E's non-casters, while 5E's casters are well ahead.
A simple example here is skills: unless you're a rogue, in PF2 you can only be good at two skills (three skills at high level, that's it); whereas every other D&D'esque system allows you a lot of broadness and versatility here. Growing from two skillls (at most levels) to a whopping three skills (at high level) is really not a lot of horizontal progression; and getting options that in practice aren't worth using (like the aforementioned Power Attack) is also not horizontal progression.