The Dark Knight and Batman Begins proved
That CBMs could be dark and fun.
Nolan probably slipped up with rises by starting DC's new dark and depressing route with rises.
Snyder decided to build on that dark and depressing formula.
David Ayer tried to make it dark and fun again with Suicide Squad but that film suffered from crappy writing and a crappy plot.
Hopefully Justice League will be dark and fun but actually have good writing and a good plot.