When left X-Men: The Last Stand to take on the Man of Steel there was something of an uproar. Singer reveals in a recent interview with Total Film that his departure left its mark and he took it hard, actually. He said:
I’ve never told anybody this, but I found the whole letting go of the characters for X-Men 3 so traumatizing that a friend, who shall remain nameless, had to take me to a secret location and show me the reels so far, just so I could make my peace with it.
Wow. That's a lot of attachment, but it also shows a lot of commitment, which is why we should probably by relieved that he's back for X-Men: Days Of Future Past.
It would seem that he approached Superman Returns, the project that took him away from The Last Stand, with the same level of attachment as a fan of the Richard Donner Superman, saying:
I was too reverential with the material. That, and I tried to put too much in. There wasn’t just a love triangle, there was a love quadrilogy [sic].
If he's owning up to being too reverential, then at least it was on his mind. Blind pandering to previous takes on a film can be pretty bad, but when a director is self-aware about it, then it might not turn out to be so bad.
Singer's return could, indeed, bode very well for Days of Future Past.