I've been a mod user for years, though only in the past few months have I begun to mod games myself. I'm not going to pretend to understand what used to happen 10 years ago in the modding community, or even 3-5.
However, I do take issue with people being this uptight about their "intellectual property" being misused or stolen when it's entirely based off of, used assets and files from, and completely made possible by someone else's work.
I get the frustration with the way Nexus acted. I understand why they did it, and even though it's not perfect, it has worked for some. For others, it's nothing more than an annoyance, or worse. Think what you will. I just question how legitimately you can claim full rights to a modification to a game you don't own the rights to.
If there's been some well-known law on this, then please, enlighten me. But it's my understanding that this all falls under "fair use". In which case, so does Nexus' actions.