I like this in principle. You are right that the "working part" of a tablet could be a bit lighter with this approach.
However, one of the great benefits of tablets is how easy they are to start working on: with my iPad, if it's in my briefcase and I have to add a calendar item, I can pick it up, start it, add a calendar item, and put it back in mere seconds.
Having it attached to a keyboard and having to mess with the wire would slow this process down a bit, I would think. Also, I can't pick up the whole package and run to a meeting quite as easily.
I agree that it will be less mobile than a conventional tablet, but some people will be glad to lose a bit of mobility for desktop horse power and price
However, one of the great benefits of tablets is how easy they are to start working on: with my iPad, if it's in my briefcase and I have to add a calendar item, I can pick it up, start it, add a calendar item, and put it back in mere seconds.
Having it attached to a keyboard and having to mess with the wire would slow this process down a bit, I would think. Also, I can't pick up the whole package and run to a meeting quite as easily.