I question the timing; it seemed rushed to get in front of Google I/O. The press had to stand behind a roped-off table of Surfaces to take photos. Clearly the hardware and software is not ready--nor does it have to be for an October-ish launch. But why did they have to demo it now when the press couldn't have their way with it?
I imagine part of it might be to just get more excitement about Windows 8 both in the consumer and developer community. Perhaps they thought that it might make more developers begin to make apps for Win8? Anyone who was thinking about it should probably be convinced by now that it's a good platform...
Someone with power allowed their ego to make that decision. It must be now, because of something that some other company is or isn't doing. Damn the engineering, full speed ahead.
All that said: take my money. I want one of each.