The only one's he's screwing over are ones by writers that aren't very good.
It's been reported that Morrison just isn't sharing what he's doing in Action Comics and because of piss-poor editorial not being all that co-operative, it's been very challenging for the writers of Superman to form a cohesive narrative with Morrison's vision.
Scott Lobdell may be a bad writer, but you certainly can't say that George Perez and Dan Jurgens are. As a matter in fact, Perez has come out in public complaining about the frustrations he had with the book:
"I had no idea Grant Morrison was going to be working on another Superman title, I had no idea I was doing it five years ahead, which means, my story I couldn’t do certain things without knowing what he did, and Grant wasn’t telling everybody, so I was kind of stuck, who exists, DC couldn’t give me answers. Oh my gosh, you’re deciding all these things and you mean even you don’t know what’s going on in your books… so I became very frustrated…"
Supergirl has been solid, and Superman's been utilized perfectly fine in JL.
Never read Supergirl, I was kinda pissed that they pretty much did away with Gates' progression of the character. And Justice League is the only other book that DC is allowing anything significant to happen to the character of Superman.
When Morrison was controlling everything in Batman's universe, other writers were still able to utilize the character effectively as well.
Because even though Morrison wasn't being as co-operative as Scott Snyder with other writers, he at least delivered a clear vision for the Batbooks when he was in charge of the line. But I would say that the Batman line is even better now with Snyder in charge and working with the other writers as opposed to Morrison being in charge.