Well, there is room there since a topic cannot have categories, by definition. Not sure it’s totally necessary, after all, when reading an email you don’t see who it is “to” unless you are looking at the top? I guess that’s the closest analog.
Perhaps it would make more sense to remind people of this at the time of reply in the editor rather than nagging them constantly about it in the docked top UI element.
I’d really like to have topic owner listed in topic lists. For the class-related stuff that I do, knowing who made the post is pretty important. People fairly often put their name in the subject (which bugs me lots more than it should).