1) Microsoft helping to kill PC gaming. Popular Microsoft PC franchises like Fable, Gears of War and Halo are nowadays only available for the XBox 360. Fans are provided no choice.
2) Pricing and reliability, it's cheaper than a Wii and especially old models break a lot. Several friends bought various revivions in the hope it would have less problems (more reliable, less noisy, less disc scratching, etc).
3) Somehow many people in the US actually like Microsoft and thus XBox, less so in other parts of the world. Mass advertising seems more effective there.
4) Microsoft buying Japanese exclusives. Many popular Japanese franchises first released on the 360, the 360 performs very weak in Japan, but it would have performed even weaker.
5) Microsoft buying exclusivity to multi-platform enginge based games.
6) Recommendation of bad coding practices which results in less optimised code as well as hinders porting to non-Microsoft platforms.
Oops, I thought it said XBox 360. It was still too early... 
