Exactly. Dual boot, triple boot, blah, blah, blah...the operative words here are boot. Why would I want to reboot to run anouther O/S to support some perticular software? You would think that the idea would be to have a single O/S that runs any software transparently regardless of the intended O/S. Unix - Irix preferred
Why would anyone want a missile that flies without a warhead? Nobody, unless it's a demonstration flight working toward a production model. Then First Flight, which flies with an inert warhead, is a significant milestone. It demonstrates that flight control systems are all functioning properly.
Everyone wants what you describe as a final result; that IS the idea. We get there in small steps, not in one great leap. This is a very important proof-of-concept demonstration.
BTW, here's another article with some screenshots: http://www.reghardware.co.uk/2006/03/16/mac_boots_xp_contest_won/
Possibly because most games run on Windows, and games are the most performance intensive applications. Emulation isn't going to cut it.