I'm in the camp that has been saying a lot but NOT ALL blame should go to Snyder. The Snyder apologists always seem to deflect and spin in a way that puts no fault on him at all... it is bordering on worship. The meddling started when WB saw the BvS UE. It wasn't what they wanted. That is when the meddling started... it wasn't during the filming of BvS. He had control on the filming of both MOS and BvS until he showed them the UE. That is when they stepped in. They felt like they had given him too much freedom.
Nolan's style wouldn't fit the DCU. I'm not sure Johns would be the answer as far as hiring any directors.