Plea bargaining is a tool of the prosecution, not the criminal defendant. Accepting a deal is always at the prosecution's discretion.
That the 5 (or often as not, 15) seperate felony charge 'real sentence' is invariably many times more severe than what is ultimately plead isn't the criminal getting away with something. The prosecutor has no intention of getting that sentence, or evidence to make most or even many of the charges stick. He just wants to intimidate the accused out of requesting an expensive trial - and 19 times in 20 it works.
We need to deter these guys before they start their criminal careers. Sending the guys we catch away for all their crimes would be a good start that would send a signal to the younger ones. Also free up the police to bust the real criminals ~ the speeders on the Beltway!