Clothing is already the single most easily personalizable thing in the game, after your own @describe, @nakeds and @voice.
There are messages you can set, which would spell out actions like that. It doesn't result in a new description - for example, you could pose or "@tease" rolling cuffs up but the way the cuffs are described wouldn't change. Still, it's very rich already.
It's a popular idea and has been discussed before, especially in the context of certain pieces of in-game clothing (not player-tailored ones) which have certain in-game effects for the wearer.
Last thought, I've achieved effects like you'r talking about with a @macro - I can enter one custom, stored, personal command which poses something clothing-related, maybe dons or removes an item of clothing, and sets a @naked with a new message, all at the same time. So, with or without actually changing whether the thing is worn or not, I made parts of my appearance when "looked at" different by resetting the appropriate @naked.
Just some ideas for you. There's already a hell of a lot that can be done today, without waiting for new MOO code to be written. Have fun!