MP count is the wrong way to approach the MF system.
Remember the increase in quality of the captured scene when you moved from a crop camera to a FF camera ? (if you did
).
Imaging a sensor not a little bit bigger but TWICE as big as the FF sensor, that's MF
With the MF system you get :
More dynamic range
More 3D look to the pictures due to a different FOV
Much more detail (lack of AA filter)
Better graduates (16 bits, although the new 14 bits cameras come close)
Better color rendition
Better control over DOF (Perfect for portraits)
REAL ISO50 and 25 (great for outdoor flash)
There are also disadvantages:
Slower to work with, no higher ISO (usable 200 and a reasonable 400)
For me (mainly models) the MF system just delivers a much better quality.