> Not the form factor as well?
Sure. The big/only advantage of the tablet (IMHO) is that you usually already have one, and a Bluetooth keyboard costs peanuts.
If I, as I said above, use a tablet/keyboard combo as a light laptop, it's only because I'm too stingy to shell out additional money for an ultralight laptop, given I already have an (ultra)heavy one. The already existing tablet was the obvious solution for casual computing on the road.