If you think about all the swiping you do with a mobile OS, and how little you would want to do that with a mouse, you realize it's not a desktop OS. I've played with honeycomb on a desktop. Sucks. Much better on my nook. Games, homescreens, web browsers etc would all need changing, and I don't think that it's worth the effort for google, and I'm sure they realize it. Touch OS's were relatively new when android got in the game. Desktops have had OS X/Windows/Linux for quite some time and are heavily entrenched.