>Bail is required to be offered in almost all cases even murder.

Not true, some people are simply remanded.

>Otherwise the police could completely destroy lives (how long will your employer let you keep your job while you are in Rikers?) with the mere charge of any violent offense, and just drop charges after a few months of you being in jail without any consequence.

People often forget that for felonies where bail is set, the case has to be indicted in front of a grand jury within ~3 days of the offense. For violent offenses, that often means the victim has to testify or there needs be some other proof of the violent act.