The more booking categories, the more trouble it is for Disney. But they have to know most people will want the MK view, so I think they will have at least two categories - MK view and everything else. If they don't make MK view a category, the front desk CMs will have to deal with the "disappointed". on a regular basis.
FWIW, I think I would prefer the lake view. I don't think the roof tops of the MK are all that attractive, LOL and I'm willing to go elsewhere to see the fireworks (don't need to see them from my balcony), I'm probably pretty much alone in that view, though.