the concept started in the middle ages. when you captured somebody, you held them for ransom. but then you would let them go on so they could rustle up the money to pay the ransom and then come back when its paid. the french king captured at poitiers being the most famous example. or richard the lionheart.
but i digress.
i think bail is possibly unconstitutional. you get arrested, you havent been convicted yet. by what right can they hold you? so im sympathetic to "anti-bail" prosecutors (like our own here in chicago). but with that is going to come increases in crime because you are likely putting people back on the street who are in criminal gangs who will return to do criminal things.
as i believe you noted before, the reasons for crime are society based reasons, and local prosecutors and cops arent the ones that can really influence that on a large scale. bail reform has its positives - not locking people up for minor offenses cause they cant pay - and negatives - letting out people who will commit other crimes again before being tried for their last crime. i tend to favor the bail reformers.