I've thought for sometime that best Superman stories in last 20/30 years are out of main continuity...Red Son, Secret Identity, All Star, etc. Heck..even the long Mark Millar run in Superman Adventures created and used its own continuity and was excellent.
The main continuity stuff just has "too many cooks spoiling the broth"...several writers and artists working on too many issues to unrelenting monthly deadlines...it's not a recipe for excellence. Add constant involvement in "big events" and ever increasingly muddled back story, it's really not easy.
So given success at all sorts of levels of All Star, I thought it would be something DC would repeat from time to time.
Give an outstanding writer and artist team a good editor, plenty of space (say 12 to 60 issues, depending on ideas of artist/writer team)...and let them tell a long Superman story, from beginning to end.
Given that Grant Morrison and Frank Quitely set bar so high..I can sort of see why DC didn't ask another team to take on challenge immediately afterwards.
But is there really a strong argument not to do it periodically?