As someone who initially liked Man of Steel just fine and went into BvS with tempered expectations (but was still disappointed), I think everyone is just tired.
Whether you like Marvel's stuff or not, it's clear they're succeeding. They're getting good talent to make movies that people like; meanwhile at WB, you have Snyder making Superman and pals look like fucking jokes. It's just kinda disheartening. I WANT the DCEU to get good, but the chances of that happening are positively remote right now. The studio doesn't care about fan feedback and is going full speed ahead on Hack Snyder's wild ride, so there's that feeling that we're only gonna get a good DC cinematic universe on the scale of the MCU once a few years have passed and it becomes acceptable to reboot it all.
At least Aquaman looks pretty good.