Rear wings/arches....

[skov]

I suspect it's largely because every other 7-alike has big fixed arches.
IVA-wise one issue might be getting the rear lights in the correct place.
I think (but I could be wrong) that the tail and indicators need to be mounted on the rear wings to get them close enough to the edge of the car, and that's going to be more difficult with small wings.
The big rear wings also hide all manner of stuff from the sharp edge/ radius rules.