The question is, do you want to run OS X/Windows apps on your tablet?
Yes, I do actually. And here's why - some day, I'd like 1 device that:
1) I can use to can run the full-blown productivity apps that I need for work
2) I can use as a media consumption device for when I'm at home or on-the-road
In order to truly leverage productivity apps that I use for work (Word, Excel, Powerpoint, Outlook, Development IDE), I need a keyboard and mouse. But I'd really like to be able to come home, and use the same device to read a book, browser a magazine, watch a movie, or catch-up on a TV show.
A device like the Surface Pro allows me to do that. At work, I can use it for productivity (though admittedly, running an IDE on such a small screen may suck). As soon as I come home, the keyboard cover gets detached, and I'm using it as a media / entertainment device. Currently, I use a MBPro and an iPad...but hell, if I could just 1 device that does everything, why wouldn't I want it? While the Surface Pro hardware isn't there yet, I think some day, there will be a device that can do all of this. It'll be light enough, powerful enough, and robust enough to do all of the above.
Microsoft's success depends on convincing people that they need to run legacy Windows apps on their tablet, even if it means hot-running, chunky tablets with lousy battery life and insufficient storage. The success of the iPad in a windows-dominated market suggests that this is not so. There were Windows-based tablet computers before the iPad - they never escaped from niche markets.
The prior Windows-based tablets didn't have what the Surface Pro has: a better form factor, a detachable keyboard, and better display technology. I'm not saying the Surface Pro is that great right now, but I do think the technology will get better and it won't be a "hot-running" and "chunky" tablet with poor battery life (btw... my iPad 1 runs hot as hell and frequently shuts down when I'm outside in the summer...and I live in New England where it doesn't get that hot).
Jobs was bang on about the usability of a touch screen on a laptop (a nice extra maybe, but not as the primary pointing device).
I would use the Surface Pro's keyboard/mouse pad cover as the primary pointing device when required, and then detach the cover and use the touch screen when desired. Having both options doesn't require that you use both at the same time