Brandeezy
Superstar
I think they have too much money invested to reboot, 250+mil in SS, 300 -400 mil in BvS, 250mil MoS, 150 - 225mil in WW, probably 175mil in Aq and 150 -175mil in The Flash. Zack's story credit is probably more a contractual inclusion and producing credit as well. I mean they said Affleck is getting producing credit and doing rewrites on JL, so its like they are trying to change direction mid-stream.
Just overall the planning and execution of their cinematic universe was rushed in comparison to Marvel, plus they have some major character changes that Snyder made that Johns has already said was stupid out right, with regards to Superman.
That's more on Nolan than Zack and the CEO of WB at the time who was an idiot who thought the idea of shared universes was a bad idea along with thinking the dark tone works for every DC movie. Then he claimed MOS would make a Billion dollars and got pushed out by the board after