Wish Switzerland would let us immigrate.....
Both the Swiss law, and firearm bans, are restrictions on liberty. Neither is an answer to the horror of mass killings, had the Colorado killer not had firearms, he could have used bombs, such as were found in his apartment. And as he was wearing a helmet, armor, throat & groin protection, there is little chance any person shooting at him would have made any difference.
Joker Holmes had a number of hand grenades that he built himself. He could have used those.
Whether he could have been brought down by someone else in defense is debateable. Many times those in body armor have simply been knocked down with the force of the bullet.