I don't know those two feats you named, must be in a splat I guess. But it's indeed not uncommon to do so.
Some examples of what I do:
- Ranged Finesse is not a feat, but an attack mode that anyone with the Precise Shot feat will use automatically. Actually it works just like normal finesse now.
- TWF users can use Two Weapon Strike at will, i.e. add the damage of both attacks (at the same BAB) for purposes of overcoming damage reduction. This is originally a Feat from HFc iirc, but we made it a generally available option.
The reasons for these two house rules are:
- archery and TWF are too weak compared to THF or similar, it should not cost extra feats to bring them closer to par.
- in case of Ranged Finesse, the feat as written is utterly useless. TWS is good, but the TWF basis is too weak.
So the main reason to change feats to manoeuvres is that either the feats are too weak, or the things the feat is supposed to improve is too weak to begin with.
I think I made more changes like that, but we have about 5000° here and I can't think clearly.