[aardvarcus]

I think they also might be serving as drip rails/rain gutters to keep the water from the roof from soaking you when you open the door. I was noticing almost exactly the same sort of step up on the roof of my Tacoma, where the top of the door forms a higher step.

Edit: Not the best picture, but you can see the raised portion on the sides by the doors which is taller than the roof.