Absolutely nothing? like 95% of all the PC gamers who only use mods, and don't make them themselves? So what, PC gamers who don't make mods, shouldn't be able to play mods either?
The people who use mods without developing them still
bought the game on PC, thus, they supported and encouraged the continued release of the series to PC. That is contribution. I have no trouble at all with the idea of people using my mod if they are, by their purchase of a game capable of using my mods, making my game platform a more attractive target for developers. If I make a mod, it makes the PC a better habitat for PC games. This is a good thing.
People on consoles who use mods without developing them would not encourage continued release to PC. They make the console a more attractive target for development, reducing the PC to the role of content development. That is a bad thing.
Further, this concept of needing a million dollar PC to run a game is simply not true and reflects the lack of research that is rampant here. You can build a mediocre gaming rig for around 500$, and a really powerful one for 1000$. The "price per performance" ratio on modern PC hardware is insanely better than most of you seem to give it credit for. This isn't the 1990s where you need to mortgage your house to buy the latest stuff. If your budget rig can't run the game at 1920 pixels wide with 32x FSAA and gods know what else, just turn the freaking detail down until it runs well. You only pay premium prices for a PC if you demand it to produce premium eye candy. The idea that the PC version of the game is simply unattainable to anybody who is not independently wealthy is pure fantasy.