Sounds like a developer that just doesn't like the fact that MS is asking them to add something into their game that they didnt plan on.
Personally, I've never really been huge on achievements, I can take them or leave them. If I earn some, fine, if not, thats ok to.
I agree that they do add replayability to a game. While generally the first time i play a game, its just for the fun of it, this gives some motivation to go back that game and try for something when I'm bored.
I do think to an extent they can put a damper on online play, but again, thats just an opinion. I dont see the big deal.
If you like them, enjoy them. If you dont, ignore them. Maybe there should just be a setting to turn off the notifications of them.