I agree with @AbyssalMonkey
In my opinion, the only people wanting an expansion with "character type" tags are those who come here to jerk off. Any other reason is sophistry to justify it.
Tags shouls be used to identify the plot and core concept.
I already see people in the comments of stories chime in with a: "This should get xxxxx tag...", just because 'xxxxx' made a single chapter appearance; even though it has no real relevance to the story as a whole. I'm sure there's already plenty of stories that presently have a tag for similar reasons -- much like how some stories may get a 'tragedy' tag just because of one sad moment.
You'd also run into the problem of who would actually be the one to police and monitor such an expansion, as well as who makes the determination of when it gets a tag. I'm not even going get into that at the moment.
Now, with that said, if you were advocating for some type of user controlled "Fetish Filter" that was hidden out of the way where people could share their own tags from a predetermined list, then I wouldn't really care. As long as it remains it's own entity that I don't have to see -- unless, of course, I were to choose to.