On the other hand, we should be so lucky if more mass-shooters try to use full auto. There are very few situations where that would result in more deaths rather than less.
The fully-automatic question comes up because of pragmatism and practicality. The guy used 1000+ bullets to fire upon a crowd. You physically cannot do that if you only had semiautomatic.
I wonder if this might have been more deadly if he had fired fewer shots but deliberately aimed each of them at a person. The percentage of wounded survivors in that shooting was atypical.
These aren't the choice you'd use for a planned mass shooting. The problem is gang bangers killing more innocent bystanders with the latest gun fashion.
After three such incidents involving children in Minneapolis in a short period last (?) year I mused on how it would maybe be a good idea for someone to start a nonprofit that brings gang members to gun ranges to train them. I think we'd all rather they kill each other than bystanders.