I'm not saying achievements are bad,i just dont care about them,or gamer score.
Some people just get obsessed about them....taking away the point of the game in the first place,especially the younger generation ( but thats up to them ).
If people appreciate a game & get achievements thats fine....i just dont see the point in buying games just for game score reasons,you can miss out on so much doing that.
Especially good games that have a great story,good exploration etc....Plus the hard work and ideas dev's put into the game...all that is missed out..especially when obsessed with gamer score. Like i said i know people who just buy games for that reason,does'nt make sense to me.
If i was dev ( obviously ) i would want to make money,but i would also want people to enjoy my work & appreciate it....& not skip most of that creativity,just to rush through to get gamer points....but thats just me

I don't think people buy the games solely for gamer score.
But if you've completed a game you love and you want to play it again it can be a good thing to check up on the achievements to find some that present a challenge or something you didn't think of doing the past playthrough and therefor give a little more replayability or just challenge to complete for a sense of personal accomplishment.
I like to enchant my items and create spells in oblivion that allow me to jump higher and further and then I try to reach the highest points in the game with the items and spells and without them for personal achievement, but it would be nice to have a window pop-up saying "You know what, you actually made it to this roof, here, have some gamer-score".
It's not truly important, doesn't do anything but you feel a little rewarded by doing it.
Killing 300 people in fallout 3 wasn't for personal achievement at all, I just played the game, and they just give me an achievement, you know what game? This is not an achievement, I didn't do anything. I just played the game without even trying and you just decide to give me one for not doing anything?
Do I feel like I accomplished something?
No.
"Doesn't Play Well with Others" == fail at feeling like an achievement.
Same with many of these achievements.