I would like to see something along these lines, but limited to something like you can increase the quality of a single item once a month (quarter?) by 5%. Make it expensive, in time, credits and resources required. Non-maunfacturable limited to a max of q125 and manufacturable limited to q200. I guess my contribution is to say make it limited to only a single 5% increase per month on a single item.
Ok, new thought. Also, limit the ability to increase an item quality to only those items that are non-tradable. Yes, this would eliminate repairing most manufacturable items, but tough, that is what the market is for! :)