My largest issue with these paid mods is the contention of a rather serious issue, as Bethesda is actually taking advantage of a IP loop hole through this. This is of course a super not cool, really bad loop hole.
Consider this for a moment; you write a book at your work place in America, you were currently receiving compensation for your time while at work, even though you wrote something that was not directly related to your work.
Now in corporate America, the company you work for can claim your IP as their own, and is also entitled to 100% of the profits. Now in this case of the modders, while not technically considered employees they are considered "contractors" in this case. Typically a contractor that is separate from the corporation as a whole can side step this issue, unless they are working with something directly related to an IP or project. If they are they are then subject to the same regulation as an employee. Parody law no longer applies in this case as well.
Paid mods is just another way to claim IP covertly and without consent. By allowing modders to sell their work through their system Bethesda is automatically entitled to their creations, this includes ideas, game mechanics, art, and anything else that they may find a use for. In this circumstance the modder has no choice but to forfeit their work under this kind of contractor obligation.
Bethesda has done this before with plenty of mods already, and in doing so scared off a lot of smart modders. Unlike a company like Valve, that will literally buy out a mod team, give credit, or straight up hire them. Bethesda is only interested in the modders work, and intends to use this system as both an acquisition and disposal system forcing modders to compete with each other for money.
I also want to submit that modifications to games are literally the frontier of game development that have spawned wonderful ideas that later led to fantastic stand alone games. For an example Counter Strike, Team Fortress, Blue Shift, and the list goes on.
Anyone supporting such an oppressive and overtly underhanded program either deserves to be taken advantage of or simply doesn't understand the ramifications of such a choice for long term development.
Paid mods are egregious and should be stopped before too much damage is done.