So a guy took several people's mods, redistributed them without permission, and got called on it? Why is this a big deal? There are several sources that provide links to game improving mods as well as guides on how to get them working. There are also several mod compilations created with the consent of the original modders. This is the (minimal) work of a guy who doesn't understand how things work.
Aside from the legality of the thing (where this guy clearly falls into the wrong, at least in the US), this guy is part of the problem that drives modders away, to the detriment of us all. The thing about creative types is that they put a lot of effort into their creations (well the better creations, anyway). Because of this, the modders feel a sense of ownership to their work. So when someone comes along and decides that something is free to redistribute just because it's free to download (which is absolutely not true), the modders are justifiably angered. Enough of this sort of disrespect can (and has) drive modders away from the scene altogether. In this case, the distributor of this compilation has pissed off a lot of modders, which is why the response seems so severe.
There is another reason that this compilation might not be a good idea. Mods get updated, even for a game as old as Morrowind. Sanctioned compilations have a hard enough time getting the latest updates integrated, so how much harder would it be for someone that has pretty much been shunned by the entire modding community to keep something as large as Morrowind 2011 updated?
As for the comment that Bethesda is the one that owns modding content... sorry. Bethesda may be able to lay claim to content created by their editor, but the same cannot be said for models, textures, sounds, and anything else created by external tools. And if you take those away, what do you have? Some scripting, dialogue, and a lot of exclamation points and error messages. Try again.
What this guy is no different than if someone posted the entirety of Penny Arcade on their own site in order attract web traffic (at the expense of the original creators). He does not deserve your sympathy.