A movie can't both be Serpico and His Girl Friday at the same time
you're too focused on the movie instead of a story. A Superman/Batman film doesn't have to go full sad or ultra bright.
It does unless you want every character to come off like they're the same flavor. One thing I liked about Wonder Woman was that it didn't really sell the cinematic universe that hard, and seemed like it was trying for its own thing. Then she got wrapped up in the big story and became a prostitute. "But if we had a good person, it would work!"... just keep putting the quarter in the slot machine, DC. Never learn.
Just because you can't understand how to write a group of characters with different personalities doesn't mean it's impossible,and using JL as proof does not help your argument
My point is DC repeatedly doesn't understand it, so why keep trying as if everything has to be like Marvel when in the past, not being Marvel scored you movies that were some of the biggest blockbusters of all time.