They are probably doing this so they don't have to add backwards compatibility to 360 games in the next console generation. I'm not familiar with the Xbox 360 API architecture, but if they were forward thinking, they may have made the 360 run an interpreter that is written specifically for the console instead of raw…
Once again, wishing someone with a heavy technical background would comment in this thread, as I'm not that person, but considering that even though the hardware is similar on some aspects, the cpu is different and at three cores having to be emulated, the architecture of the console is also a bit different from pc's. It…