And as was pointed out upthread, BB was the first time that Batman's origin had been told in detail in a movie. Superman's already had that, plus all the multiple recent versions in other media.
I just don't see any compelling need for a new origin movie. Now if you give a hypothetical non-origin movie or two a chance, whether or not they include or directly continue from Singer, then there's a much stronger case for one. 10 years from now, the Donner film will be half as old as the character, and about two generations old. There's a much stronger case for a new origin movie then, if you're willing to be patient.