When someone has a 360 and a PS3, and they then choose the 360 game over the PS3 game for the achievements (even though they would rather play the PS3)... I believe MS has accomplished their goal.
If the game is good then playing it through again should be a non issue, and getting those lost achievements back should be fun and entertaining. If it is bad then does the achievement really hold any merit anyway?
In the end the value of an achievement is only as great as the one the individual who achieved it places on it. Does anyone truly believe that MS cares about the value you placed in accomplishing your achievement? Games are trivial diversions from reality. Achievements are trivial rewards gained in those trivial diversions. In the end it is all trivial... If one believes time playing video games is time making money (though there are a few who do it professionally) then something is askew here. If you truly believe that time is money then playing video games is definitely not something you should be doing. We pay to play games, not make money. We pay for the diversion from reality that comes under that beautiful package. $60 for the game, $300+ for the console, $$ for Live, $$ for accessories, $$ for ISP, etc... We play to make all that worth it. But the actual time spent is not making us any money.
Though in the end I love to see that "achievement unlocked" banner pop up while playing my trivial game and wasting away my money