Modders should be able to ask for donations, nothing more. They should see this as an opportunity to create great content based off of a much larger and more established game. If they want to get compensated, perhaps their great content will take off and one day they can make their own standalone, but until then, donations only. See Counter-Strike, DayZ, Day of Defeat, Team Fortress, Insurgency, et al.
1) Valve half-assed the implementation (of course) so that existing mods couldn't be changed to "pay what you want" (a.k.a. donations) unless you deleted and re-uploaded the mod (thus breaking auto-updates for anybody who had the old version).
2) The real tragedy here is that Valve's also turned off the "pay what you want" option in addition to the listed price options. So if I do want to accept donations for my mods, even understanding my "cut" is only 25%, I can no longer do that.
