If you actually go back and look at the sentencing research, you see that to a large extent courts do impose consecutive sentences a large majority of the time.
One of the other witnesses was testifying and using a sort of banal example of multiple offences against mailboxes. If you add up each offence, you can risk throwing away or giving less weight or no weight to other aspects of sentencing that also need to be taken into account. That's the danger you come up with, and then we're left with this ridiculous sort of U.S. system where someone can get 400 years in jail, which is ridiculous, right?
You need to have a balanced approach that takes into account all aspects of sentencing, not just retribution or not just denunciation.