I think the whole thing with Batman in the Justice League is that he is supposed to be the "human only guy in the scary costume" member of the team. The contrast with the other characters is why it works. If he looked like Superman or Wonder Woman, what would be the point of having him around? It would be like the Superfriends cartoon where all the heroes were interchangeable.
Any good superhero universe should be able to have something for everyone. The Batman movies can be dark and solo character focused, and the Justice League movies should be about these heroes interacting with each other and fighting threats that individually they can't win against. Ideally, we should be able to have both.
As for meta humans, there are a lot of great Batman villains who are meta humans. I would love to see GOOD versions of Poison Ivy and Mr. Freeze in a Batman movie. I would love to see Clayface. Do we just want to keep making the same old Batman movies over and over again? I loved Nolan's trilogy, but he was clearly running out of ideas and steam by the time Rises came out, because he closed Batman off to the meta human characters (and took the Lazarus Pit away from Ra's) and we needed to reboot things over again. Maybe we would get fewer reboots if we weren't so rigid in what types of stories we allowed to be told in a Batman movie.