There are many blog posts at the moment about attunement; love it or hate it.
Like all things there is a benefit, and a cost to that choice – which changes as your playstyle and perspective changes. I like attunement as I can know that the player has at the very least done some content.
I dislike attunement as it means I cannot gracefully skip content to the stage my alt was/is at. There is no right answer, which is probably why attunements were removed. Too much of a grey area led to angst, which then absorbed far too much time.
Overall I like attunements more than I dislike them, and think that they could have a valuable place in world of warcraft.
While I agree that creating very large attunement paths is a barrier which is difficult for some, and could even be problematic for raiders who switch characters (or whatever) there was something great in the story aspects of the attunements.
eg. Getting the Karazhan key was interesting from a story perspective. It took a small amount of additional time and effort, but it was entertaining and interesting.
If the attunements were part of the general story, in content which was not repeat-gated (eg. one after another) then they could return with my support. Perhaps the attunement is for the 5man to raid step, rather than for each raid step?
Perhaps also start the stories and the attunement chains as the leveling experience (e.g. the Marshal Windsor UBRS key), and therefore the story plays through the experience, which leads into the raids.
Make it so that the players would be foolish not to take the opportunity (Wrath Gate questline, or the Battered Hilt quests) and you’ll see more game lovers than haters.