@sjc1017
Actually it's quite understandable why they haven't done anything with Warcraft. They drove off the hardcore Warcraft fan.
Those currently playing WoW, the vast majority have no clue, nor any interest, in knowing Warcraft lore. Of course with all the retcons, one can hardly keep up with the lore to be honest. Retcons may be an occasional, rare thing in an ongoing fictionsal universe, but Blizzard has done it way to many times over the years.
In fact, little of the story is even presented in game. One of the major storylines when WoW began was Varian's disappearance. Blizzard constantly promised that the storyline would be finished in game (was the Missing Diplomat questline). However, a game that charges $15 a month to play decided to wrap up the storyline in a series of comics that cost about $30 total to see completely. There are numerous other examples as well.
And then you get to the fact that WoW gives so much experience so fast, that even if a player doesn't wear heirloom gear that they will gain so much experience as to need to skip over zones from the order they were originally designed to present the story. But then the vast majority of players don't read quest text anyway to get any of the story, they merely see "Go get 10 of item X" and do it. Bosses and mobs in dungeons may as well be white square boxes with the title "Raid Boss 7 of Tier 12" over their head.
I think Blizzard knows that a WoW 2 or a WC4 would likely bomb out as the current playerbase does not have that same loyalty to Blizzard as the playerbase Blizzard pushed away after Kotick took over once had.