Actually the pre-played sales of xbox games did skyrocket in conjunction with the xbox 360 bc compatible games...
initially
At least that's what happened at the store that I work at.
Although this doesn't really help getting MS or their developers profits, but it sure did help giving gamestop/eb games their increased pre-played quotas.
so bottomline is that Microsoft isn't really benefiting from bc, aside from bragging rights...
because a good portion of the games that people want to play on the list is either discontinued/out of print or just hard to find nowadays.
the only game people play for bc is halo2... that's it... really...
The only real thing that bc is good for is when someone is feeling nostalgic, and wants to play that rare gem in the plethora of xbox games, they won't need to drag and dust off their old "unsexy" xbox system that they have hidden in their closets...
I also want to point out that most people that bought an X360 did ask about bc, but I really don't think they will use it... to them, it's just something "good to know"...
either or, they've already given enough games to be bc-ed, if they stopped and focused on something else to improve gaming on the X360, then I'm all for it.
on a side note, a microsoft rep came to the store today with some pamplets about present and upcoming attachments for the x360, they have the camera and the HD-DVD add on in their product line already. although no MSRP is given on those two, the featureset seems nice... sadly, he had no clue what those were for