I'm not entirely sure what I think of this. On the one hand, it's wonderful for the users that are selling their mods in the first place and it allows them to turn a hobby into a source of income. They're also likely getting proper access to the API and that'll translate into less strange bugs and more possibilities. And, with support from the developer, the mods have to be high quality (the developer's name is on the line too) and easy to install. Not everyone finds mods easy(or safe) to install, so this already allows for a greater user base. They're likely not going to be expensive, and a small premium is not too bad a cost to ensure that at the very least, the mod won't break your game.
On the other hand, yeah, it's paying for something that you're not guaranteed to enjoy. In traditional mods, you try it, and delete it if you don't like it. No risk (except maybe to your save files). Now, that's a risk you also take when buying the game in the first place. But it's at least a full game, and you can also gift/sell it if you don't like it. It's something you expect to risk on. A small add-on by a third party isn't something you expect to risk on. Oftentimes mod developers may have really great and creative ideas, but not necessarily the experience/skill to pull it off in the same way a proper developer would. And you just can't tell until you try. And developers of major quality mods already get money from them, via either donations or those sites that give you money when people click on your link. Microtransactions are dangerous for people's bank accounts because the amount looks so small that you don't quite add up in your head what you're *actually* paying.
So yeah... I dunno. I guess in the end it boils down to how good the mod developer base is vs how much the user base is willing to break their bank account.
