Where do the addons download from? If they host them themselves, on their own server, then this is a clear violation of copyright. It doesn't say one way or the other, but judging by how things are worded, text in the screenshots, and how it doesn't show what site the addon comes from and/or a link to that addon's download page on that site, it seems that this is the case.
Also, note that the lack of link backs to the *real* download sites is just one of the reasons why many authors dislike and fight against updaters like this (like wowmatrix, for example).
Didn't wowmatrix add linkbacks though? Updaters are a bit of a lose-lose situation unless they work with the site owners (and to date none of them really do). Either it's copyright violation, or it's bandwidth theft.
So why doesn't anyone really mention <addon updater x>? Because they're not going through official channels to ensure that author copyright is respected and bandwidth bills get paid.
Yes, they did, after they found out that people were bitching about it. It's still in a somewhat hidden spot, though. But I apologize for forgetting to mention that. Sometimes my brain works faster than my fingers. ;)
wowmatrix did ultimately adhere to every major complaint from the community of authors, but they did so kicking and screaming the whole way - and waiting until mere days before Curse shut them out of their servers.
Compliance isn't good enough. Cooperation would have served them much better.