Why is Unchained not going to be Vanilla?

Hi folks,

As i've read and seen a lot of videos about Unchained (which led me to buy a pack)

I noticed that a lot of people prefer how the game was with the old system, some even say alpha, yes i know alpha had many flaws too, but why not just roll back like WoW did and slowly progress and add the features we as the community/players really want in it?

If this has been answered already just close the thread, but i'd like to see the statement from the developers. (If anyone could link me that) Thank you :)