I see DC villains becoming League-wide threats all the time. Sinestro in Sinestro Corps War, Superboy Prime in SCW and Infinite Crisis, Black Adam multiple times, Lex countless times, Ares, Darkseid, Braniac, etc.
But big world-threatening stories get boring. They swallow everything up and leave tight room for meaningful characterization. More exposure for sidelined villains would be cool, but I don't need a rotating cast of god-conquerers to emerge to feel satisfied with DC's villains.
Identity Crisis saw the death of the spouse of one B-level League member and all hell broke loose. That's much more intriguing to me.