If you're going to build a bunch of building symbols, why don't you do some gable roofs as well as the hip roofs? Hip roofs are what folks autogenerate en masse by applying a bevel -- if you're going to the effort, then you can stand out from the crowd. Gable roofs make more sense to jam together gable-end-to-gable-end; doing that with hip roofs gives all sorts of nasty drainage and gutter issues for your myriad builders.

Whether you're overdetailing them is totally dependent on the scale you intend to use. And if you later reduce them to the point where some details blur, you'd be better off having used simpler shapes in the first place - simplification by blurring just leaves a muddy, indistinct result.

Are you planning on shading the results, once you have them placed?