You'll forgive me for trying to inject a little reason into a nerf debate (an impossible task, probably), but that's what I'm about to try and do anyway.
Yesterday, mages, warlocks, and shadow priests were up in arms about the changes on the test realm to the tailoring epic outfits. Blizzard was experimenting with adding ability stats to the armor while nerfing spell damage, and tailors went ballistic over the changes. And so, within a matter of hours, Eyonix announced on the forums that the changes had already been reverted and would not go to the live servers.
Now, yesterday I said the nerfs weren't that big a deal, and since then, I've seen some good points that say they were-- lots of people spent lots of time and gold getting just these recipes together (some even leveled tailoring for just these pieces), and it definitely presents a problem to make serious changes to gear that people have already sacrificed a lot for.
On the other hand, there were good reasons behind the changes as well. As even a few tailors have said, these crafted pieces matched up to the Tier 4 and 5 pieces, and I see problems with basically requiring clothies to be tailors to be competitive in the endgame.
Many warlocks cried the most about the changes, but because +spell damage doesn't translate directly to most of their DOT spells, in many cases, they would actually be the least affected (Update: In hindsight, I shouldn't have judged how affected anyone was by this change. But that's not the point of this article-- read on.)
But my point now isn't to argue whether these sets should have been changed or not. What I want to point out now is that being outraged on the forums and yelling at Blizzard about something that's happening on the test realms will actually impede the developers' abilities to make good changes on the live ones.