Just like the current ATMA grinding, there is an extreme amount of luck involved in overmelding. You can get lucky melding your first forbidden slot, just like getting lucky with an ATMA from your first FATE. Or you could be unlucky, and like last night, go 0 for 40 trying to meld a Control II into my AF leatherworker pants first forbidden slot.
To get the first level of crafting mastery available, HQ'ing 2-star items and such. I would have loved to see truly crafted AF+1, using drops from dungeons or HM Primals. Using this logical path, crafters are working to better themselves. there's a luck component still, but if someone doesn't want to hope they get a dungeon drop they need, buy it off the market boards. They still have determined how much time they want to invest, either by running dungeons or selling items to make the money needed to buy the item needed to upgrade. In addition, a crafter could progress at whatever pace they want, piece by piece or doing it all at once.