JD could play any character and do it well. Since it is Warcraft, you'd think they would start with the whole Human vs Orcs type deal...well if they were smart and start from the beginning so at least new people who haven't seen or heard of this game can understand a bit of it.
I'd really rather have low-profile actors for this movie.
If anything, Depp can be Budd. I think he's a fantastic actor, just not... suited to a srs fantasy movie.
I agree that unknowns would be more immersive for many of the roles in the movie, but if they're going live-action, and with Hollywood being a business -- unfortunately they'd have to spring for at least one or two big names to reinforce ticket sales.