I was thinking that a FF lens used on crop camera is sharper in the corners because it only sees the centre of the lens. See the new Zeiss Otus 55 f/1.4 lens. Most people believe that's exactly what they did with this FF design.
The lens designers could make a lens that has a much larger image circle (maybe 1.5x the size of FF), this would make the lens' corners sharp at full aperture on a FF camera.
The drawbacks that I see would be the size (thickness and weight) of the lens, but ignoring that why is this approach not taken?
IMO your comment about the OTUS is partially right. I am shure that Zeiss did NOT have calculad a MF lens but they just used the Distagon formula which applies a negative front lens(or group) to create a retrofocus design. This allows a longer light path through the lens and gives additional opportunities to correct aberrations.
Usually the Distagon "fprmula" is a retrofocus design used to keep the mirror area clear from lenses to avoid any "conflict". A MF wide angle for a (D)SLR needs the same construction but for different reasons.
The main idea behind the OTUS construction is (again IMHO):
* use a retrofocus design to get a longer light path which can be influenced and
* use different special glasses (i read sth. about 6 different special glass types!)
which can be placed in the longer light path due to the retrofocus design.
To the OP:
A good idea might be to use a MACRO LENS for MF with an adaptor on a FF camera - macro lenses are usually much better in terms of correction than other lenses and give higher resolutions than their "standard" counterparts. As others said: MF lenses have lower spatial resolutions for a larger image circle - the magnificaion in postprocessing is smaller to gain the same "final product size" so there is (was?) an advantage of MF.