The show probably faced its biggest problem in its unusual story line. For the time that Superman was created, the story was considered wonderful and captivating. This was probably because it was one of the first stories of its kind. Since then, hundreds of sci-fi plots have been written, and the public started to accept only the somewhat plausible ones. The thought of an invulnerable hero who can fly, see through walls, and run at speeds faster than jet planes is hard to accept in the nineties.
People find it much easier to relate to something a little less strange.
Batman's story is a little less outlandish, and is probably a major reason for its lasting success. When Bruce Wayne was very young, his parents were mugged and murdered as he watched defenseless. Emotionally scarred, he vowed to fight crime like this when he was older. Using the inheritance received from his parent's wills, he bought the materials to create weapons and artillery needed to make him into a powerful crime-fighter. He created suits of armor that could not be penetrated by bullets.