Trying to exploit the actions of a lunatic in Arizona to support your unrelated political agenda is the worst kind of political opportunism. There are people who are insane. We as a society need to deal with this fact. We also need to understand that some insane people are a threat to themselves and others. As a society, we have both a right and a responsibility to see that that those people who are insane and a threat to others get treatment.
Providing better treatment and handling of the dangerously insane is the only step we can (or should) take to prevent another tragedy like the one in Arizona. As long as their are dangerously mentally ill people roaming the streets, they are going to figure out how to harm others.
The vast majority of mentally ill people do not present a threat to anyone. There is a small subset of mentally ill people who present a threat to themselves and only themselves. There is an even smaller number of people who present a threat to themselves and others. It is very unpleasant to face these facts, but we have to face them one way or another.
If we refuse to deal with the fact that there are insane people out there like Jared Loughner who present a threat to others, then we are going to have more Tuscons.