I believe that the desire to make higher quality equipment rarer and more costly can be done without RGN and with more resource sink and player satisfaction.
The current system has 3 RNG levels for crafting.
Basic is 80fine/20good, and stays there for residents despite tech.
Craftmanship+ specialty shop:
80good/20 exceptional
This roughly means that every third item will be exceptional
Engineering + specialty shop:
40good/60 exceptional
This roughly means that every other item will be exceptional
All these odds are fine and appear fair.
But because of RNG it is entirely possible to have a run of 15 items with none being exceptional.
(I have experience with this from making hundreds of cotton cloth armor)
This is quite frustrating and produces lots of worthless unwanted good equipment which floods the market with little demand when exceptional goods are also available.
My suggestion is to switch from RNG to resource costs.
Instead of one craft button you have two.
One with the base resource costs that produces the lower quality option.
The other with twice (for the 40/60 ratio) or three times (for the 80/20 ratio) base resource cost that produces the higher quality option.
So with Engineering and a tailors shop you would have two buttons-
One that will cost 5 cotton cloth and produce a good quality cloth armor piece.
Another button that will cost 10 cotton cloth and produce a exceptional quality cloth armor piece.
This maintains the over all odds of getting a piece while increasing the resource sink but letting the crafter know what they will get instead of having them roll the dice to see if they are lucky or not.
This reduces the issue of crafting unwanted good items and prevents the market being flooded. In addition with a reliable way to get exceptional items it is more likely to see them for sale in the market instead of hoarded as rare event pieces.
This same base idea can be extended to enchanting.
In the enchanting case the first enchant on an item requires one of each reagent, the second requires two of each reagent, the third requires four of each.
Even if you keep the RNG odds of loosing an item the loss is quantifiable in its cost to replace without having to worry about more cumulative RNG gambling.