I really don't understand why you refer to the whole change of disarm immunity as a Warrior nerf. Blizzard has changed the entire way disarm works with the change. Not only Warriors got "nerfed" EVERY melee class got nerfed. I think that when you think deeply about it, you might see that Warriors actually got the upper hand.
Now, everyone can be disarmed as weapon chains no longer makes you immune, therefore Warriors, Paladins(retribution mostly), Shamans(enhancement mostly), Hunters and Rogues can be disarmed as well, I'm refering of course only to the classes that might melee you(the ones that actually care, feral druids don't really care about that I guess).
So, who can disarm? ONLY Warriors and Rogues, who can be disarmed? Everyone! NO one is immune anymore. Why is that a nerf?! You'll be disarmed as a Warrior and be ineffective for X seconds? So what? Warriors are one of the two classes that can disarm. On top of that you can get the ability to have another disarm duration reduction(if they stack, even more fun) and ONLY Warriors gets the extra ability.
You should only expect disarms from Warriors and Rogues.
Warriors are all "nerfed" equally, so it's fair in that aspect.
Rogues have a totally different mechanics of disarm, if you disarm them first, they wouldn't be able to parry for 10/5 seconds and they wouldn't be able to disarm you back(Unless I'm mistaken and you can parry without a weapon, though I doubt it).
Enhancement shamans ARE nerfed against Warriors/Rogues in that aspect. They can still cast, true, but you force them to cast when YOU want them to. Same goes for retribution Paladins. If you are fast enough to disarm that Hunter, he won't be able to wingclip you as well(yes, he has a ton of other abilities to use, but then again, Hunters don't really care for melee much).
Explain to me again, how is it a Warrior nerf when EVERYONE gets affected the same, but Warriors are on of the only 2 classes that can disarm?
The way I see it, Blizzard has returned disarm it's viabilty, and gave Warriors and Rogues some love.
The only way Warriors are truly nerfed by being disarmable, is in PvE, I don't think there are enough disarming mobs for that to matter.
If you want to sacrifice your Savagery/Mongoose/Crusader/+healing/whatever enchant on your weapon for weapon chain(Again, if it stacks with WM) to have lower disarmed periods, that's your call, just know that EVERYONE else will still be disarmable, no matter which enchant did they bring on theirs.