It seems to me that increasing gun ownership restrictions makes a lot more sense for preventing suicides/crimes of passion than it does to prevent rampages.
I don't think it's too reasonable to base any laws on things which are so insignificant in terms of life loss as these rampages are. I feel the same about most terrorism; it simply isn't a big enough problem to justify the reaction it has obtained.
Mostly, I feel that if you have to reach for rare and emotional events like rampages to justify your political interests regarding gun control, you clearly are not looking in the right places for your reasons. If you want to ban guns to whatever extent, that's a perfectly legitimate goal-- but don't outright manipulate people who are hurting. It's crass and feels like going to someone's funeral so you can sell life insurance.