I agree with you. The small bump to things like attack rolls, damage rolls, and save DCs from hitting levels that bump your modifier are noticeable, and playing as a wizard in the campaign I'm in right now I can tell you I'm champing at the bit to get my spell DC that one little bit higher because it's the difference between some of my spells having no effect or outright changing the flow of combat. Getting that boost and also some of the big-hitter feats like Tough or War Caster would be a bit much. It gets even worse if you're getting the benefit of the 2 points ASI as well as one from the half-feats.

On the other hand, though, there's a huge gap in the power level between feats, and I'm not sure I'd necessarily feel the same way if the feat chosen was Shield Master, which is one of the weaker of the full feats. I might also be more inclined to set aside a list of the more flavourful feats like Chef that the players could just get for free without the associated ability boost and let the players just pick one for free as character building.