It promotes public and police safety. With statistics that indicate it's one of the best ways to ensure civilians and officers alike see less injury. The only people who fight against this are people with stuff to hide.

Honestly I think tying qualified immunity to its use would be enough. If the camera gets shut off during a non violent interaction then the officers testimony and QI are compromised. Officers are allowed to lie to the public, and I can understand the necessity, but they can't lie to the court. Shutting off of the camera would only be too obscure facts or hide illegal practices in the court trial.

Obviously if the situation becomes physical or violent. Exceptions will exist for officer safety. Any video from prior to the altercation will have to be handed over, or the damaged camera to show it got so damaged it couldn't be recovered.

Of course these actions would require law enforcement, government officials, and ceos to not rely on illegal actions of officers. So the likelihood of something that benefits everyone and only hurts criminals getting passed is quite low.