Not a bias against the function but a bias against the cost. A good stock will run $100+. The hinge setups are all $100+ as well. So that's a $200+ investment. And I think folks are generally happy w/ the stormwerkz adapter plus aftermarket stock availability but since the stormwerkz requires a dremel and fitting on a lot of guns (a pita and a trip to the gunsmith for a lot of folks... +another $100), it's pretty stiff a barrier to entry.
And the total cost of a stock setup being $200+ for existing options other than the polymer fab (~$120) and the OE wood/beaver fixed stock ones (~$100 these days, plus $20 UTG or Apex butt pad extension) which is the mid price point. Even the czech aftermarket folding hinge mechanism to install the OE fixed stocks as folding runs $120+.
And then the budget is keeping the I bar folder and wrapping it w/ padding/paracord and then using a buttpad for less than $40 all in if you don't have any items on hand...
Since the OE hinge mechanism is perfectly robust and works well, I don't think it necessarily needs to be replaced (by not R&R you save any potential receiver to adapter and other fitting issues too -- just screw off and screw on essentially for the hinge pin nut).
And if you can come in with a mid-level price point (you could sell your stocks at the same price as others in the $100 range, yours just wouldn't require an adapter and hinge) with steel internals, you'd really have differentiated yourself in the market. I think the fab stock is ugly and just have been unable to subscribe... But I think their pricepoint of ~$120 is the ballpark you should aim to bring your stock to market at fully installed however it is you design it all to come together... If really unique/spectacular, I'd think you could probably not loose many customers if you keep it under $150, but beyond that I would suspect you'll have a significantly smaller customer base just due to cost.
Lastly, please recall that folks are buying the VZ2008s @ ~$300 once accounting for the value of accessories... And somewhat like the AK mentality w/ furniture, convincing folks to spend more on the stock than they did the gun is a tough sell. The forend is the same story, but due to heat that's kind of a "have to" if you plan to shoot your gun a lot... And the fab polymer is the midprice option there and probably moves a lot of units.