For example Power Attack is in all 2H builds at some point. The same is with Deadly aim for archers.Also Augmented Summoning for conjuration wizards, sorcerers, and summoners. So tell me when does it go from being overpowered to necessary. I'm speaking of the overall effectiveness of the character employing the use of such feat I'm comparing them to other options.
The word I would use to describe all three feats you mentioned would be 'Core'. They are Core feats for those archetypes you mentioned, and there is not a bad thing about it.
They support nearly everything those archetypes you mentioned do, have reasonable entry reqs, and offer additional choices and options for a bit of deeper play (with PA and DA, at least).
My group's houseruled that power attack and combat expertise are kinda like combat maneuvers. Everyone gets to use them for free.
The reason is that those feats are prerequisites for almost everything usefully combat related (especially in 3.5) and they don't really make anyone overpowered as they involve trades in allocated bonuses.
So for us, at least, I guess they are necessary.