Some people are fundamentally against the take on these characters and are using it to justify their judgment that the movie was bad when in fact plenty of higher rated movies are just as flawed in terms of technical filmmaking. The only real difference is the artistic approach and that's really a matter of taste, which many are unwilling to admit. Some of them want pure escapism that depicts a romanticized reality. But the truth is, Snyder's approach of humanizing the characters in a world as flawed as ours is just as valid and does interest people.
DC's characters are more established in pop culture and therefore have more ingrained opinions about their approach. Then you have the genre trend being dominated by escapist takes. Even Nolan's trilogy had a great sense of idealism with statements like anyone can be Batman and make a difference. Many are rejecting Snyder's assertion that the real/flawed world would be no better with superheroes, and furthermore they would unavoidably be a product of the real/flawed world. Therefore, any idealism will be met with controversy and conflict. That is how the way the world is, but some people what pure escapism whereas others appreciate acknowledging how things really are. I want to see Snyder direct X-Men. Snyder does have flaws as a director but so do most superhero directors, which is why TDK is still lauded at the top of the genre. Yet, people are using any opportunity to push their aesthetic bias by conflating anything negative and use any opportunity to assert it's the approach that's the issue.
Perhaps people go into these movie wanting to get away from said real world.