Yeah, actually, I think it would have made more sense for Jackson to have done movies of stuff like the Quenta Silmarillion or the Lay of the Children of Hurin, because they're so much less fleshed out, so the inevitable added dialogue and such could only expand on it.

But there's no way in hell Christopher Tolkein would ever let them adapt any of the stuff that wasn't part of the deal with JRRT way back in the day.