Pretty sure in the pantheon of Warcraft beings, the Dragon Aspects (of which Deathwing is a member) are like Demigods. I'd have to look at the Lolore, but I'm pretty sure Deathwing also deceived the others into giving up some degree of their power, allowing him to become the strongest. I think that's been retconned or changed in one of the books though.
Anyways, if the Titans are Gods, the Dragons are pretty much Angels, and Deathwing is the equivalent of Lucifer. I fail to see how he's 'less powerful'.
In regards to the WoW Movie, aren't people who have no idea what WoW is going to see trailers for this and assume it's connected to Lord of the Rings? Icecrown is pretty much Mordor in Winter, and everything from the design of the Citadel to Arthas' armor design screams Sauron. Not to mention the elves and orcs running around.
I just think there are more interesting things you could do with the Warcraft universe than put the spotlight on what is arguably the most blatantly Tolkien-esque parts.