IT would require a lot of work I am sure, but it is possible.
Take City of Heroes for example, large MMO, with the ability to
A: Design your own bases, from a UI much like the one presented here.
B: Create your own missions.
It can be done in an MMO. Now, will they do it? who knows.
As far as having your screenshots up as pictures, good idea, but how would you implement it? Usually, having something like that, and having it be visible for every other person that visits usually requires that they have the pictures on their computer.