As any reader of The Dragon from the old days knows, there's a large number of people loose in the world who can create some really nice fantasy art. And ten thousand times that who... not so much.
So, given that this is a cooperative deal between Turbine, Atari, WotC, Hasbro, whoever... why not get together and get some artwork in that does a bit more justice to the DnD property? I really don't see a need to always see something copied essentially from a game instance. Look at the Risia splash screen art. Really nice.
Not saying we need busty Vallejo babes, which would not hurt, but we could use some fantasy art to wow us every so often. Actually, this would be even more effective for new content like new monsters. Have a really great scene sketched up containing clues to the next mod's content.