hmm, this seems to have touched a PC nerve!
I am not saying they are vital, I just find they give me a bit more longevity. It's only a personal view, and we are all entitled to our opinion. I quite liked the challenge of getting the New Vegas hardcoe achievement on my gamer card!
It's not a "PC" thing at all, I dislike them platform-agnosticly
Personally, I think that Achievements (or trophies, or whatever) glorify minor accomplishments (Such as the NV hardcoe mode, which is basically "Play though NV again except have half a steak every 3 weeks") while stopping people from considering larger accomplishments that developers may not have immediately considered. They stifle imagination and promote an OCD-esque completionist standpoint without actually completing anything. I've heard people say they finished oblivion because they got all the achievements, for example.
I remember when gaming was fun because the games were enjoyable, not because you can perform simple tasks to raise imaginary numbers on an imaginary card for some false sense of accomplishment.
Plus, yeah, that notification really kills immersion.