They ignore how audiences--contrary to Hollywood's wish--are not expecting all characters to be dark, psychologically damaged or morally bankrupt, or view them as normal.
What they are not ignoring is a track record of audiences paying to see this
and not that
I don't know where fans get this notion that some fad or fashion just runs riot through the entertainment industry for no better reason than that these people are somehow disconnected from popular enthusiasms and feel like amusing themselves by burning huge wads of cash to prove how clever they are. That business is as Darwinian as you can imagine - people make big mistakes (and everyone remembers them for quite a while), but when something fails big just about everyone draws one conclusion: don't do that again. The reverse is also true.