Then either the Microsoft quote wasn't MS, or they were misinformed (Finance people instead of tech people?). I'm guessing the reason it only works with the top games is some amount of patches are needed per game on top of the emulation, and MS will release patches as they create them.
So you won't be able to put in your old games and play them unless the emulator has been tweaked to support that game, but eventually it should get tweaked to support all your back-catalogue.
So you won't be able to put in your old games and play them unless the emulator has been tweaked to support that game, but eventually it should get tweaked to support all your back-catalogue.