In his defense he didn't original want the Hobbit to be stretched out into three films, that was from execs who wanted to milk the book for what they could. The Hobbit would've worked as one movie since the book it's based on wasn't very long.
However, the Silmarillion reads like what it's meant to be, a bible of the world of Arda. It tells many stories and gives details on why things are the way they are in LotR and The Hobbit.
It could work as an anthology of animated segments, I'd enjoy seeing that.