Sorry, but that is contrary to human nature. We will always want to use the most effective and modern tools available for whatever task we undertake. It's terrible that some civilians misuse firearms in such an aggressive, offensive manner but the truth is that most do not.
If AR-15s weren't available there are other semiautomatic rifles out there. If semis were gone then it's easy to waste a room full of people with a pump action shotgun or lever action rifle. An accomplished operator can dump plenty of rounds with a bolt action and box magazine.
Singling out particular weapons is pointless because it fails to address the root problem, that people who shouldn't have access to guns do. Tighten that up and things may change in the US. (For example, in Canada, our screening process would have included a call to his ex wife and likely resulted in the Orlando shooter not being able to buy firearms or ammunition legally)