MFs for VWL, BCV & BWV aren't all that far apart. They are all "hotel-like" resorts with hotel-like services & amenities.
I think the reason for the difference between them is just that the BWV make up a larger portion of the BWI/BWV resort than the VWL does of the WL/VWL combo or the BCV of the BC/YC/BCV combo.
DVC shares the "common" costs of the resort with the non-DVC resort(s). Disney proprates those costs betwen DVC and the Resorts by the number of units with perhaps an adjujstment for average occupancy. Don't know the exact formula they use. FWIW, I expect dues at AKV to go up a little faster than the others once it is completed. (I think the developer pays a subsidy to keep initial dues on the low side to help sales. Just my opinion - it could be wrong).