The current craft system is basic stuff, and I've got a feeling that the higher the grade will go the more it will stabalize. For a fact:
Currently tier 1to 2 armor and weapon crafts need the item of a tier lower ( which can in turn be found as drop in dungeons)
So lets assume that with higher dungeons the drop rates of items will get lower and lower to a point when it would be faster or easier to craft an item along the whole chain than to hope to get one as drop. Its a more or less typical thing for this sort of Cheap Riders of Icarus Gold
Add up to this the fact that its hard to get the best stats for your class as for now, meaning that if the first part is true then later on theese "junk" items wont be simply sold to vendors but rather recrafted in hopes of getting better stat on a higher level tier.