The Surface is the exact thing Microsoft needs to stay relevant for consumers. And if Microsoft can start selling their own hardware, in the end they'll be better and more profitable for it.
What does SemiArrucate thing Microsoft should do? Stay the same course that has seen them losing marketshare for a decade?
But the biggest problem for Microsoft is that the market is shifting. Between smartphones and tablets, people just don't need PCs as much. So Microsoft is desperately trying to be a factor in those markets. Shrinking the PC down to the size of the Surface isn't a bad idea, but it will make OEMs very uncomfortable. They are feeling the same market pressure to get small and mobile.
If you look at Wikipedia's statistics, Microsoft represents about 75% of visitors: http://en.wikipedia.org/wiki/Usage_share_of_operating_system...
I imagine that in 2002, their share would have been hovering around 95%.
So yes, in this case MSFT would be more profitable - do you think they can make more money creating a superior experience, without crapware, where they can absorb the entire margin of the device.
Or can they make more money shipping software to OEMs who have historically stuffed it full of crapware, failed to release timely updates, and only give MSFT a tiny cut of the proceeds?