With Rebirth incorporating Watchmen characters into the mainstream DC universe, one has to wonder: Is any good story safe from being butchered? None of Dark Knight Return's sequels have been anywhere near as good as the original and, one could argue, have lessened the quality of the original. Marvel burned the Ultimates universe to the ground despite it being the basis for their entire cinematic universe. The Star Wars prequels ruined the original trilogy (but not before the "special editions" did it first). Convergence changed the ending of COIE but not before Infinite Crisis ruined it ten years earlier. Now, there are plenty of good stories that haven't been touched or at least haven't been ruined by "follow ups": Kingdom Come, All Star Superman, Batman: Year One, Old Man Logan, Civil War (though it is getting a sequel), New Frontiers, etc. But even that can change at any time. DC could decide to do a sequel to Kingdom Come anytime they want and make Superman a killer or something. Ditto a New Frontiers sequel that gets into the Nixon years.
Now, Kingdom Come Superman was incorporated into the mainstream DCU back in 2008 in the pages of the JSA with no real harm to either one. And Old Man Logan is currently being incorporated into the mainstream Marvel universe and it remains to be seen what effect that will have on either one. Though he seems fairly isolated at the moment (as are all the X-Men characters due to movie reasons). What story is next? No story is safe! Some of these ideas work in the mainstream universes. The Miles Morales Spider-Man, for instance. He works regardless of what universe he's in. But that is an out-lire. Other ideas only work in the context of their universes (May Day Parker). To incorporate them would raise a number of questions about the future of the mainstream universe.
This isn't about Rebirth and the changes associated with it, per say. It is about taking classic stories and trying to "improve" them by either going back to them or incorporating them into the mainstream universe. When DKR first came out, it was seen as a potential future for the mainstream DCU. Ditto Kingdom Come. No longer. Every "What If" story now gets it's own universe. And as a result, it gets a "sequel" even if it doesn't need one. Other stories like Year One work well on their own whether they are part of continuity or not. Frank Miller considers it the origin for Batman in his universe and it was used as the origin for the mainstream universe after Crisis. Before Watchmen isn't considered canon to Alan Moore or hardcore fans of the original series but DC does. But was it necessary? Does it add or take anything away from the original story? What little of it I've read, it doesn't contribute anything to the original one way or another.
What is your opinion of every classic story getting a sequel or prequel or being incorporated into the mainstream universe? Does it take something away from them? Does having Dr. Manhattan being the "god" of the DCU make it harder to like Watchmen now?