Mayber there should be a size limit to the hair. Anything over a certain amount won't be able to be forged. It would be a good I idea to do that for flames too. :P

The problem is that the "Size" you talk about depends on more than 1 or 2 parameters. Limiting one or some of them isn't the solution at all.
Also, about the user-friendlyness: it may sound rude, but item forgers are the ones who has to understand how that works (you can adventure yourself to learn it, it's not that hard after all). And yeah, we've talked about some improvements and add ons to the forger, so some new hair styles can be actually made.