The 3.5/Pathfinder Handbook

[Saph]

3.5 Power Attack: Take as large a penalty as you want (often to AC, to a maximum point) to add incredible amounts of damage to your attack, enough to one hit kill most enemies and thus making melees a threat at high levels).

That's not how it usually gets used. Most players don't use Power Attack in ubercharger builds, they use it to take a penalty to hit harder, which is what Pathfinder Power Attack does.

The issue here is that you're looking at Power Attack's usefulness in regard to super-optimised builds designed to kill everything they can land a full attack on, instead of looking at how it gets used in casual play. The fighter in our Pathfinder party uses Power Attack in EXACTLY the same way as the fighter in our old 3.5 party.

True, but sometimes you can barely hit someone so you could in 3.5 PA for 1, but in Pathfinder you either use or don't.
This is a loss of versatility.

This is a fair point. I'm personally still not sure about whether core-wise, Pathfinder's Power Attack is a buff or a nerf. You gain in terms of rate of return, but lose out in versatility. Hard to say which is worth more.