It's been possible for the indie games market to "explode" ever since it first came to be (1979 to my knowledge). It's just prior to 2007 it took real talent, hard work and a shitload of luck to get anywhere in the game business. It was because of the work of developers prior to 2007, the few skilled and lucky ones that could get anywhere in the market, how they built up and helped shape the market and created "tools" such as Steam to help remove all the old barriers that they themselves faced back in the day, that we got the deluge of no-talent, no-brained, pink-haired, narcissistic hipster douches that now stand around exclaiming that they created the whole indie scene. Fuck everyone else that came before them.
In the early 1980s one out of every ten "indie developers" could get their game released. Today it's one out of every thousand, and we're STILL being flooded by shovelware. But I digress.
Mods are a similar thing, they could have been and HAVE been sold since the early days. Unofficial mods and levels for Doom, Quake and Duke Nukem scooped up, packaged into a retail box and shipped off to the stores, that was a thing. It was due to generous developers that the mod scene was allowed to thrive in the first place, but from what I can tell it was always done with the intent of monetizing off the best of the modder's works. People seemed fine with that, the best mods became commercial products. The new status quo is that ALL MODS become commerical products, and people have a problem with that.
The biggest problem I have with this change is the precedent it sets. If all mods are to cost money, what's to stop them from having patches and compatibility fixes cost money? How much further can they push this? That's why I brought up the sun and air thing - people aren't looking far enough ahead to see how ugly this can get.
People HAVE to draw a line in the sand, otherwise we'll all end up as unwilling employees of the Crimson Corporation. The mod thing is a small battle, yes, but it's a battle nonetheless.