Some people tend to post what genre their post is, some don't. Personally, I like seeing the tags there so we know what we're about to listen to, or at least get an idea of it.
Probably wouldn't be a hard rule, but maybe something added to the sidebar like "Please add a genre description. if you remember to."
Whatcha all think?
EDIT: For clarity, all I mean is formatting post titles like "Weedeater - Wizard Fight [sludge/punk]"
To me, genres are kind of a lie. Some music falls in to a clear genre, a lot doesn't. That's why you see some shops where almost everything is under 'Rock & Pop'
You can pretty much always get at least a little descriptive though (all music is a part of some tradition), and even if you personally wouldn't know what to call it you can always refer to the artist themselves on bandcamp (the tags at the bottom of the album page) or sites like rate your music where people will have tagged everything.
Personally I'm with OP in that I'm for the tags. Every good music forum I've ever used has them as they make searching easier as well as just giving you an idea if you'd want to click on a particular topic or not.
Genres are big circles on a giant never-ending Venn diagram of types of [thing in question]. Multiple genre labels will often apply to a single piece of music, and you can trace the influences that led to a certain genre's emergence.
Don't think of it as categories in the music store. Think of it as a taxonomy that primarily exists to help you find stuff that's similar to what you already like.
Thanks for your input!