I understand why you won’t let modders make dlc pieces, since that would mean people would get them for free. I absolutely do not begrudge you making money. Would it be possible for you to let modders use the skins of those sets but restricted to pieces that don’t exist already? (I know nothing about video game design or modding)
But if they can’t make the missing build pieces, then would you please give them to us? Those should be some very easy Bazaar sets that you could make available.
Vaulted ceilings in the vanilla and early dlc sets, 2 x 2 gateways and gates in anything other than Stormglass, the sloped walls for Arena (which I know many of us have wanted since it was first released), and countless other very obvious missing pieces would all be very much appreciated.