I completely understand your point, but in the particular case mentioned, I have to disagree.
There was no reason for a plea-bargain in this case. Once he left the scene, the doubt is over. Why did he leave the scene? Was he drunk? Have drugs in the car? I don't know. In any case, leaving the scene after an accident with injuries isn't even debatable anymore. That should be enough to convict him.
Also, somewhat unrelated, any felony (and some misdemeanor) driving related sentence should be an automatic lifetime ban from driving. This guy could have afforded to not drive. He wouldn't even need to become a cyclist. He could have afforded an alternative.