Way to not pay attention. Valve took 30%. Bethesda decided they deserved 45%, and left 25% for the mod maker. 30% is Valve's cut on nearly everything, so this is not unusual or odd. If Bethesda had taken 20% that would have left mod makers with 50%, and the outcry would have not been there. If Bethesda had decided to forgo a cut in order to sell more copies of the game, everyone would have been cheering the 70% cut that mod makers received.
Should Valve have anticipated that 25% to makers would look bad? Yes. Perhaps they should have refused to roll it out with that initial revenue split. They certainly should have put better moderation tools in place to control graft and mod theft.
But the idea of charging for mods is completely fine; we've been doing it for years already with games like Dota and TF2. What's a community created hat? It's a mod that you pay money for.