I wouldn't say the 360 is doing that much better than the original XBox did hardware sales wise from the long perspective. Sure more Japanese gamers were pushed into buying a 360, but this due to some high profile Japanese game developers being contracted by Microsoft to develop some exclusive games, but love for the 360 or Microsoft IMO has nothing to do with this.
It was already expected the 360 would sell faster initially than the original XBox did (the PS2 sold faster than the PSX as well at similar pricing despite PSOne still being available), this due to the original XBox being discontinued and left unsupported for over 2 years.