BLM is more complex. That movement fundamentally couldn't have kicked off the way it did without being radical, the very moment you switch to "make the police better a little bit" you'd have sucked all wind out of the movement because black people who have suffered at the hands of the police would not have participated, they hate them and do not see it as fundamentally repairable. And they're probably correct because the country isn't reformable and was built upon a fundamental foundation of their repression.

You're right about burn out eventually setting in on movements that can't achieve their goals. But this is where zooming out and looking at things hollistically is necessary, the act of performing struggle caused a great deal of cultural change in attitudes to the police. It should be viewed as one of many battles in a string of battles that leads to something eventually rather than a failure in isolation.