Now what you're asking for is a bit of a stretch. Sure they can re-colour items of clothing (that for the most part is a simple image manipulation in a image manipulation program like photoshop), followed by a bunch of code similar to how dyes work with hair.
The real issue is that you would like to change the actual model of the clothing.
Right now I believe each piece of clothing is a model rigged to contort to a pirate's body and mapped out to the player model's rigging. In order to have rolled up sleeves the models will need to be cut up into individual pieces (so a pair of sleeves, the waist and for long coats the lower half) so that these can be changed and mixed, giving the full freedom to customise. Lest take the Sea Dog's jacket (because I love it) right now it's one model but cutting it all up for the maximum amount of personal changes would bring it to around five to eight models.
- 3 variations of sleeves; long sleeves, elbow sleeves, no sleeves; or 6 if you want to go asymmetrical.
- 2 for both closed and open jacket. On a shirt you'd have 3 with buttoned, unbuttoned and open.
So while I agree with your idea, it may be technically impossible without a huge increase to the file size. I believe dying clothing will come eventually but I also believe it would be better resources spent on full unique additions that fill in those desires.
