Maxor you're pretty angry sounding. I'm not a Miocrosoft fan. I don't own an Xbox (or a playstation or a wii, and I never will), but they have their reasons for dropping Xbox Life support. If they are to be believed, as retarded as it sounds the backwards compatibility was preventing them from fixing up their current network, allowing things like more than 100 users in a friends list.
Sounds like a programming fail, but if the only way forward os to drop the old they need to do it eventually. And yeah, I see this as an advantage of PC Gaming (at least as it has been. Dunno about these programs that rely on a central server, though that can be patched out: see Aliens Vs. Predator 2)