I already mentioned that once you go away from donations to direct pay, you lose fair use and a bunch of other things!!
It isnt like this is some crazy "Oh, I dont like that, URRRGH!" poop slinging thing here. It's about "Hey, doing that will seriously ruin EVERYTHING because then lawyers HAVE to get involved!!"
That thing where Bethesda sued the maker of Minecraft? Know why they did it? THEY ARE LEGALLY REQUIRED TO, TO PROTECT THEIR TRADEMARK. Why? Because that's the way the laws are written!
Introducing direct-market mods opens a legal pandora's box the likes of which the people arguing FOR that system simply have no comprehension of! No, it was poison-- absolute poison.
And when you get down to it, the real issue against the donation model boils down to "I dont want people to say that my mod is worth 0$, I think it is worth more than that."
Having feelings hurt is not worth calling down nuclear war using attack trained lawyers-- because THAT is EXACTLY where direct-paid mods WOULD end up.
The attack trained lawyers are what would have fully destroyed the modding community, as everyone would have to protect their IP like a mother hen, or risk losing legal protection of that IP-- Because that's the way the law works. Even when using copyleft licenses, you are STILL having to resort to being a mother hen about it-- because you have to constantly expose incorrect use, and seek remedy from the courts when discovered, or else you lose the legal protection on your IP. (Look up
Laches doctrine, and
Equitable Estoppel. If you DONT aggressively go after people who misappropriate your IP, then you cant sue them later, because they can use these defenses to torpedo your suit. That's why the attack trained lawyers ARE NOT OPTIONAL.)
That's why the EFF constantly is sueing the pants off people misappropriating GPLed source code, et al.
Seriously. Just use the donation system, PLEASE. For a safer, saner, happier future for modders now and later.