So, just my two cents on categories, having recently completed the omnium challenge!
I'd argue that they could definitely be slimmed down, but then we could think of some more! Wife-lovers, cheating and cuckold could all be united under 'Infidelity'. They are all, basically, the same idea, surely? Same with Novels and Series. Watersports, Uniform & Medical could all be ditched and directed to 'Fetish'. I agree with a previous post that strap-on counts as "Toys". And, Monster sex, horror and supernatural could be one single category too.
Is "Straight sex" really a useful category, when all heterosexual encounters that are not "Gay male", "Lesbian", "Bisexual" or "Trans" count as "Straight sex"?
(Personally, I'd ditch interracial, but that's a personal view; I don't find interracial sex distasteful, but I do find stories that reduce Black men to objects that service white women as bulls icky, and they seem to be the vast majority of stories in that category!)
And after the cull, there would be room for new categories! We could start a forum thread for suggestions, then site admin could take a view.
My suggestion would be "One Night Stand" - "One single night of passion. Meeting sexy strangers on work trips. Friends giving in to long repressed urges. Nights out ending with unexpected consequences. This category features one off, one and done encounters that are never repeated!"