Couldn't a bit of this be dealt with through the "genre" tag? I mean the basics at least? By parsing the tag and choosing the EQ preset based on that?

I'm sure it could, except it's precisely what I would NOT want to do.

My system sounds great for any genre. It's only specific albums within a genre that I would want to alter. Just because it's "Rock" doesn't mean I want to turn up the bass. I might want to turn down the bass on one specific album, but not change it for most of my collection.

For instance, let's say I've got my system sounding perfect with the hijack Bass adjustment at +4. But for Madonna's "Ray Of Light" I want the bass turned down two notches. So I would group-select all the tunes in Ray Of Light, and in the comment field and add something like "@BASS=-2".