'Cos drop ships are spaceships based on helicopters.
Looks a bit hokey to be honest. An original design would've been better.
Well Blackhawks, Apaches, Chinooks, Merlins, and Sea Knights all have wheels, and I want to say more military helicopters today have wheels vs skids, so it makes sense.
I do prefer the skids look from the original though, if it aint broke don't fix it.