There are two issues with the Genesis' left to right burners.
One is they have the knobs on the side of the grill, and a lot of people object to wasting that extra real estate for the knobs, where burners that go front to back can have the knobs tucked out of the way along the front of the grill.
The other issue is indirect cooking, where on the Genesis your indirect area is a narrow but long strip down the middle of the grill. If the burners were front to back, you could cook with one burner and have over half the grill surface available. Of course, if you cooked on the Genesis with only the back burner, you would have a lot of real estate left for indirect cooking, although typically you use the front and rear at the same time.
The front to back seems like it would be the better configuration, but keep in mind there are times when the middle section works out better, especially if you are cooking with a rotisserie. Since the rotisserie runs left to right over the center burner, you can leave that burner off, use the front and back, and cook along the entire length of the spit.