If intent is no longer an element of the crime of murder, then the criminal law would be drastically changed. Accidents, even ones involving people having seizures or heart attacks, etc. would result in the same punishment as the most heinous murders. Our common sense of justice finds mercy for the child murderer, the retarded murderer, the murderer who was reckless but never intended to cause death, etc.States should have a "it doesn't matter if he is insane or not, he is still guilty and thus will get the same punishment anyone else who committed mass murder would get which is the death penalty or life without parole in a real prison" verdict.
Doesn't mean all these people escape punishment...but even if I supported the death penalty, I'd reserve it for the blackest of crimes. So for me, I want a trial if Loughner is going to be executed.....I want to see whatever evidence there may be that he might have been able to control his behavior, and did not.