I'm all for net worth being used to buy skins, I personally would like to see both official and community skins cost something to use net worth up and then reset it every wipe. I know by having them all listed in game is convenient and easy for players to access but having a system like you mentioned by browsing the workshop, getting the ID and entering it into a GUI will eliminate most of the junk skins.
For workshop skins if someone adds a skin then it could stay in the database for 3 months, if that skin doesn't get purchased again within that 3 months then its removed from the database until its added again. I believe this will keep the popular skins in the database and keep loaded skins at a reasonable level.
Released skins can remain in the database but as mentioned should also cost some net worth to unlock them for use.