Nor Treblig - Dec 31, 1969 at 19:00
Personally I'm really not a fan of achievements popping up in the game, but I am pretty sure there are quite a lot of people out there who like achievements in one way or another.

Although Ron didn't like those in particular I think achievements tracking the progress of the overall story are an easy way to get statistics about the game.
I.e. look at those from MI2:SE:
You can see that 55% completed the first act and two third of those the next (big) act. And then nearly all of those finished the game.
what is one + one?