It wouldn't be much of a multi-pedal if it was 'up off the floor!'
I agree that something like you mentioned would be very cool, but with so many knobs/sliders/keys/(or strings) already available to your hands, and there being other desktop options available, the MP201 carves out a big niche being on the floor (ground-breaking even :p). The MP201 is very versatile on the ground or desktop, but all that power in pedal format is really what sets it apart from anything else on the market, and for the stompbox crowd like myself, it is completely unrivaled.
Every function of the MP201 can be controlled by foot, so the single Knob is really only useful as an alternative to the foot treadle/switches when adjusting by hand. I use the Menu when building patches, but rarely the Knob as I often do it all standing up with my feet, and the menu is clear and bright enough to see comfortably from a distance, and even editing hands-free becomes very intuitive.
That all said, I wouldn't be surprised if Moog did put some kind of desktop/rackmounted version out at some point in the future; my guess is that it would be an upgraded MIDI'fied CP-251. Personally, I'm holding my breath waiting for an MP-2001 Space Oscillator with lots and lots of CV outs and switches and treadles!!

(<--thats not embarrassed, its from holding my breath... haha)
Synth bass guitar rig including MS-20 filter clone, Paradox TZF, MF101, 102, 103, 107(x2), CP-251 and MP-201