I disagree, I think WoW at it's core has plenty of substance. As I've said before, if they make the Warcraft movie to be a movie for people who like movies, it will do fine. If they make Warcraft to please it's fans it will stink. JJ Abrahams has it right with the Star Trek series. Make the movie about the story and the people and forget about whether it adheres to all the Star Trek rules to keep the Trekkies happy.
That means they will need to change some things around and won't be 100% faithful. I'm sure no matter what there is going to be that group that is "OMG, the warlock had blue fire and not Green!!! That ruined the movie for me !!!" Video game movies have sucked because they have normally been aimed at the players and that doesn't mix well for the other 99% of the movie goers.
I personally hope they do the movie LOTR style, where they plan out a 3 part series from the get go.