I think it has to do with the time involved. Your plane comes into view close enough for a skin and now my computer has to search for skin 18 of the 190s. It takes x amount of time to find it and add it to the plane shape. Now double the number of skins we have for the 190. How much longer 8 it going to take a middle of the road computer to find the right skin and add it?
More of a speed thing than a space thing.