I'd argue that they're choosing the surface for everything BUT the keyboard. They're buying it because it's pretty much the only laptop/tablet replacement in the 12' range with the specs it has. Everyone else still mostly has 10 or 13' designs, which feel either too small, or too large when used as a laptop replacement. The keyboard is always the negative in any reviews for the surface as it just bounces around when you type on it and doesn't feel sturdy at all... I grew to like it when I used it, but I still don't understand why you wouldn't want an identical form factor with superior materials and a hinge mechanism, but to each his own I suppose.
Also, you can't seriously think that the vast majority are choosing Surfaces over other devices... It might be the most popular compared to other brands one on one, but overall, sales of OEM devices TRUMP sales of the SP3. Again, no numbers here, but I fail to see how MS sells more Surfaces than all of HP/Lenovo/Asus/Acer/Toshiba/Samsung/Sony etc - that's just wishful thinking imo.
If MS does keep the current type-cover form factor, would you be opposed to them making it out of some sort of plastic/magnesium finish with actual chiclet style keys? That's a compromise I could live with at the very least.