I mean, without being slave to Batman's history, he's not necessary to tell Batman stories. You need Alfred as that stability in Bruce's life, you need Gordon as that connection in the police, other than that, you can take the core of who Batman is and those characters and go off on all sorts of adventures without needing others from his past. You really don't even need the Joker, he's part of the mythology, but he isn't necessary to define Batman, it's just a character people are really use to from comics and shows and all. If Robin never existed to date, it's possible no one would ever think, Batman should have a sidekick at some point.
To me, the only integral things for Batman movies are the things that define the Batman character, and the only 2 people that you need their type of character involved in my book are Gordon and Alfred for the reasons I said. After that, depending on what you do for a story, you could get away with not using anything else. Should they, I'd say no, it's nice to see characters you're familiar with, just saying they could do it and it would still work.
