That makes a lot of sense, D, yeah.
I know Valve's done it before -- they saw their stats indicated a certain section was too hard on X difficulty for a majority of gamers, so they turned it down a bit. If I recall, they did this on HL2 Ep 2 on the final battle -- which is one hell of a hectic non-stop battle; especially if you don't abuse the quick-save system.
I'm sure there's probably been other tweaks, improvements, and balances made in Valve games as well b/c of what they found in stats, too -- such as TF2 and Left 4 Dead.
In some instances, instead of making the game easier --
Valve's even made weapon do less da...weapon (shotgun) against a "Tank" enemy.EDIT:
So, I think Achievements can be MORE interesting to the dev's than the gamers. I think it's nice if I hit an Achievement and all -- but I often don't aim for them. I play -- and if I hit one, cool. Though, on L4D -- I actually did try a lot to get Achievements more so than any gamer before -- since the game's really lacking on content, as is.