>>105214619And he played the character as quietly insane, which was the treatment Burton was going for (in a world which was clearly itself insane, which is why Burton was hired and why he cast Keaton).
To be honest, a Miller-lite version wouldn't have worked. Even Burton's first movie, for all that it made 11 times its budget back, got a lot of criticism at the time for being too dark and not like the Adam West version, which was still in reruns worldwide and the de facto version of the character to that point. As silly as the Schumacher movies were, they stayed in that same world (it's just brightened up because of all the useless cheap power generated at the power station being built by Shreck) and it's still pretty dark, just played for more obvious laughs than before.
Without that, there couldn't have been a progression to Nolan, and there couldn't have been the Batfleck that came after (which is a Miller-lite version and total garbage). You should be glad Keaton didn't want to play it Miller-style. It would have been absolute shit and killed the franchise before it ever began. No Batman, no Steel, no Spider-Man, no X-Men, no Batman reboots, no Superman reboots, no MCU, no DCEU. Nothing. You'd have had 30 years of movies about Jack Nicholson standing next to women even he probably couldn't get in real life with a seven-figure payment.