I said Other, because what I want depends on the map. generally, I'll take any feedback I can get, but sometimes I want feedback about an idea presented in the map and maybe not so much the gameplay, or I know there's a couple issues with a part of the map and don't really want people only focusing on that one most-obvious problem.
I've got better at it over time, but with specific advice I find people will suggest that I change what started out as the core design idea for my map/building/project. (this applies to more than just Quadropolis) It's hard to change your original idea, even if it doesn't really fit anymore. It's valuable advice, but if it's one of the only things suggested, the user might just not change anything and abandon the map thinking it's terrible.
Like the short-lived "user skill" option, I don't think this needs to be a category for submitting nodes.