All films need to be projected with sufficient light (i.e., 15 foot lamberts) but especially those with a deliberate and intentional dark palette. It’s possible that the reason for the complaints was that the theatre hosting The Batman wasn’t projecting sufficient light. Yes, I’m bending over backwards to allow for the possibility that the people who complained may have been amply motivated. I doubt it, but I’m trying to be generous.
Note: The above photo of a sign explaining that Greenberg refunds would have to be limited was posted within a 4.3.10 article titled “Big Greenberg Divide.”