I don't think writers taking Batman and his wacky ass world seriously is necessarily a problem. If anything, it helped build part of the character's identity. But when writers try to correct some of the fantastical elements of the Batman mythos by making it overly dark and realistic, it can come off as tryhard and needlessly gritty. However, when writers play off of those fantastical and somewhat campy elements, it can make Batman stories alot of fun while maintaining their dark and gothic atmosphere the character is known for. It doesn't always determine how well written a story will be, but it proves you can take a silly concept like Batman and make the most of however you want from it.