I understand some of the nostalgia about attunements

I understand some of the nostalgia about attunements, aside from the "forgetting how annoying they were" factor.

First, they were lore-rich questlines leading up to the raids.  Many of the raids in the Wrath/Cata era suffered from "because it's there" syndrome with the raids.  A new raid was released, and you just flew on in.  It's a serious disconnect for people who enjoy the raiding and the lore of the game.

Second, they were incredible accomplishments, which felt rewarding.  Those raids that get lead-ups these days come from either the zones or complementary dungeons (Twilight Highlands/Bastion of Twilight and Dragon Soul/Deathwing, respectively).  Finishing the story of cheap wow gold a zone doesn't have quite the same impact as those quests which go above and beyond in making a story which encompasses the world.  Likewise with finishing dungeons; we've finished dungeons.  We always finish dungeons.  And we know that after we finish that dungeon for the quest, we'll be back there tomorrow for more gear, and then the next day and the next for valor points, ad infinitum.  The impact is lost.

Finally, I can understand the attitude of wanting to sell wow accounts and separate "serious raiders" from those who weren't willing to work for it.  I've pugged far, far too many players who probably wouldn't have fussed with an attunement; having some mechanism keep those folks out of the pool of raiders sure looks attractive after they volunteer for your raid then drop out two bosses in.

(I'm not saying I agree with that last point, but I do understand.  Ultimately, those people are a server-culture problem, not an attunement problem.)