This mindset is the encompassing reality of all video game modding for over two decades. Modders choose to make content for the sake of improving the game. That sole motivation keeps things unblemished from the motivation of churning out garbage for a quick buck. You change that and people who previously made stuff purely for the sake of it suddenly decide to take down their offerings from places like Nexus and try and charge for it across the board. It sullies the whole point of the hobby and will slowly kill modding if it gains traction. And yes, I can decide it's not worth my money, but it doesn't change the pervasiveness horribleness of the situation. I don't buy DLC either, but it's still managed to ruin so many games and is still progressing to the point where we have microtransactions and locked on-disc/in-file content in full price games at launch.
This isn't work, it's a purely voluntary hobby and extension of a game with an accommodating built-in tool kit. Furthermore, mods aren't subject to the restrictions on actual work. Nobody mods to make a living of any kind, but that means that licensing for mods would be a complete nightmare if you introduce a mandatory financial aspect. You've got people potentially selling mods based on other people's mods and mods have no obligations of quality or IP infringement avoidance. Throw some Assassin's Creed or Marvel-inspired items in a sold mod and charge for it and you have a situation where the modder is benefiting from another company's property. Then what happens? Legal action? Tight moderation of what types of mods are allowed to be sold, followed by modders being lured into the whole thing then limiting their mods purely for the sake of money?
The mindset that every little thing people choose to do within the framework of something else deserves money is poisonous. Money is poisonous, particularly so in the context of a hobby that historically thrives largely because it has nothing to do with money, but rather is purely about fun. Modding shouldn't be thought of as "work" or a money-maker. That mentality is completely counter-intuitive to the rise, popularity, and point of mods. If you enable it, people that don't even feel that way will naturally gravitate towards trying to get a slice of the pie.