Eh, what are we gonna do, stick anyone who has a hit and run in jail? Jail should be reserved for dangerous people, not someone who commits a hit and run. They had no way of knowing it would turn into a serial thing.
Edit: I should add that purposeful bodily injury is a small subset of hit and runs that would be different than just a regular car crash that damages a vehicle or structure. This case appears to involve multiple attempted vehicular homicides, which is far more serious than a hit and run, which typically just involves fender benders