Police rarely find murder / assault weapons this would allow them to track the assailant and find where this key evidence was hidden. Better evidence could mean a better justice system.
That said, our current justice system usually gets a conviction even when there is no murder / assault weapon. Clearly evidence just isn't that important to the justice system.
More Surveillance will probably lead to more accurate enforcement of laws, all else equal.
We already have old, broken down, and innocent guys walking out of prison 31 years after someone at the innocence project collected the exculpatory evidence that the state was supposed to have handed over to the defense 31 years earlier. Why would the state be more likely to fulfill their obligations to justice in this regard when that evidence is digital? I guess I just don't see that behavior all of a sudden changing because cameras are involved. In fact, cameras have been involved in the past, and the videos have still not made it to the defense in discovery.
Long story short, all else is definitely not equal. When it is, I'm sure a lot more people will exhibit less discomfort at the idea of the authorities retaining film in perpetuity on everything they do 24 hours a day, 7 days a week.
What else are you dreaming of?
As it is, and always has been, all this stuff is to the disadvantage of the individual, not lessenig the burden of proof. Anything else is PROPAGANDA!
The problem isn't the techniques, it's that law enforcement in America seems to now be built more around profit than law abidence... And I doubt increased surveillance put in for the best of intentions wouldn't ultimately become coopted somehow by these interests too.