if they(manufactor) puts a driver seat lower it allows more people to fit in and drive the vehicle. It will appeal to more buyers, if they crammed it in higher, the steering wheel clearance would suck and turn most people away before even driving. the passenger side is higher to be able to see over hood.
my land rover rear seats sit about 4 inches higher than front seats, and front seats sit a lot higher than compared to the jeep. everytime i get in the jeep i feel like i am down inside the thing and cant see over the hood.
leg room is lacking in the drivers foot area in the jeep IMO as well, its fine for smaller people, hell of a lot better than a lot of cars even still! the jeep gives a good bit of headroom i think though