Burton's movies led to Batman and Robin, so that goodwill was eliminated. Just like how the Reeves movies went out with a whimper rather than a bang due to "Quest for Peace".
Nolan's ways led to the misguided approach of MOS, BvS and Suicide Squad, and even TDKR didn't come off as a good ending. So again, not the best legacy.
Raimi's movies ended with SM3...
The MCU is the only one of its kind with its scope, scale and ambition.
Yeah, as I wrote earlier, Batman 88 and Superman 78 were good movies but were false starts. Less visionary directors didn't get them and ruined their legacy. Yet they did prove that it was possible to make good superhero movies, so their legacy lives on.