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]"
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.