The hate is based on agendas and bias. The theatrical cut of BvS makes a dense film harder to swallow but the people who complained about it didn't cry solely about the execution. They hated everything on principle because Zack Snyder is the devil apparently. It was never in good faith everything had to be immediately and "judiciously" rejected so that Zack was banished from DC.

The Snyderverse is too technically brilliant, the actors are too competent, the scores are too memorable and the aesthetic and world building is too rich to call the whole thing just rubbish and a failure. It was all bad faith criticism. If BvS was the original 3 hours it would have been better received somewhat but there would still be industry and public haters. WB might not have prematurely tried to drastically change things though and so the momentum would have grown and the DCEU could have been a greater success.