> If someone is let out on bail, and commits another crime, then their bail should be posted higher.
If someone is out on bail, they are presumed innocent of the first alleged crime, and will still presumed innocent of the second alleged crime if they are charged with another one when bail for the second charge is set.
Bail is not a pre-conviction punishment, and using it as such violates the due process clause of the 14th Amendment (or the 5th, if was the federal government doing it), the confrontation clause, and the right to jury trial.
> The constitution only prohibits "excessive" bail
No, the Constitution prohibits a lot more than that; it's true that the prohibition on excessive bail is the only prohibition specific to bail, but it contains lots of other prohibitions that you can't just use “we’re calling it bail” to evade.
People can be subject to pre-trial detention. Violent offenders are sometimes denied bail, entirely, if they are determined to be a a safety threat to the public. There exists precedence to detain people prior to trial. If the situation gets to the point where crime becomes de-facto legal then this precedent should be used to curb repeat offenses.
Would it hold up to constitutional scrutiny? Who knows. But interpretations of the Constitution change. A hundred years ago people would probably be baffled that the Constitution was used to justify gay marriage and abortion - interpretations change and adapt to new ideals and values. As people say "the Constitution is not a suicide pact."
If someone is out on bail, they are presumed innocent of the first alleged crime, and will still presumed innocent of the second alleged crime if they are charged with another one when bail for the second charge is set.
Bail is not a pre-conviction punishment, and using it as such violates the due process clause of the 14th Amendment (or the 5th, if was the federal government doing it), the confrontation clause, and the right to jury trial.
> The constitution only prohibits "excessive" bail
No, the Constitution prohibits a lot more than that; it's true that the prohibition on excessive bail is the only prohibition specific to bail, but it contains lots of other prohibitions that you can't just use “we’re calling it bail” to evade.