If you brought over the ability to get desktop apps on Windows RT with a simple recompile, you bring all that garbage with it, and if the thing gets even remotely popular there will be malware for it
Ah, come on. With a bit creative thinking (instead of political thinking, what MS did) you still could get the best of both worlds. How about a "professional mode" on WinRT devices: They can't run Win32 except for Office, but, you could unlock the ability - with huge scary "at your own risk" banners if needed.
Bang. You would have a kick-a$$ device for the absolute beginners, and for the pros. Problem solved.
Win8 could be great, yet MS took the most anal way with it possible, with every decision.