I saw the Q n A session at Blizzcon, can't remember where, youtube, I expect, and they answered a lot of things.
Firstly, the reason it's being done from an alliance perspective, is that, even if every single warcraft player on the planet goes to see it, they're not going to make back their budget spend even. They NEED to attract non gamers to come see it, therefore you're pretty much stuck with a human lead, really, for normal people to 'get' it.
They did however say that the FIRST movie would be more alliance focused. So maybe a sequel can redress the balance.
I seem to remember it is set about 20 years before the start of WOW, so yes, its a Warcraft movie, and not a WOW movie.
I'm kinda hoping they don't load up too much on big name actors however, I think good 'new' actors could really do well, and fill the roles suitably.
The lead of Legendary Pictures did say that he cast the Superman returns guy for that reason, and that worked.