They already do have categories in the tabletop terrain category:

I think down the road there may be less a need for more categories, than a need for subcatgories within the present groupings as the products within a general group grows.

Right now the only thing that disappoints me in the props section is that the propane tank from the 'bits of Mayhem' set was not included, but maybe it'll show up in another pack later ... industrial bits maybe when the pcon sets are retired? I am always raiding sets for such parts. Maybe others would like to have such a pack as well.