Well at the minute all categories on MSP need more images
It's quite difficult to foresee how this site will evolve, customer-wise spoken. I have a large (well 30 or so) Brussels city view shots at DT, and they don't sell at all. On the other hand, my tropical sunsets even at 1200x1600 sell great. In my humble opinion, a stock site has to have a unique selling proposition. If it's just about concepts done in a light tent, well there are myriads of sites just offering that. And then, let's not mention Bryce.
I had a talk tonight with a friend who is an inspector at one of the "big" sites and he advised me not even to upload to beginning RF sites as the market is taken already. But for a while, I disagree with him. Let's just test the waters.
But I'm affraid too if we only see more pencil shots in a light tent here, the site will just vanish. A designer that needs those kinds of stuff can better subscribe to DT as, I guess, we all post there already.

Running an RF site has also to do with marketing. I can't imagine that there are no designers around that won't want city and culture shots. What we can do now is just upload a variety of images and see how it goes.