What about such things as vibrator panties? Strapon? Bonds? I think we need this lingerie category because of them.
They'd also work as misc items, of course.
I suppose the question here is going to be "where do we draw the line". There's always going to be scope to elaborate the clothing model. If we have underswear, do we want a separate slot of bra and panties, for instance? In which case, why not break armour down by body part? Do we want an earring slot as distinct from rings and jewlery?
You can make a case for all of these, and probably more, but the code still needs writing. Unless anyone's ready to volunteer, I think we probably have higer priorities.
Of course, we could look at solving this in the general case with some sort of XML file that defines what equipment slots exist and what items they can accept, which would at least solve the "feature creep" aspects of the problem.
But we'd still need someone to write it.
(or course, the big appeal for a system lke that is the possibility of doing a paper-doll style inventory screen somewhere down the line. But again, I'm not convinced that's a priority).