Yes, you would almost have to create a world of love to make love work. If all of society were a loving society, the love would reach to those who might commit the crimes. People are less likely to lash out if they are loved.
I hear the many of you thinking love a silly answer. Bottom line is, though, it is a big factor. And, if we are serious about stopping these things, we should be looking at the things that make a difference. Love might sound silly. Love might be discounted as silly. But, if you really want to get serious about solving the problem, you might want to consider the things that do make a difference.
Love is one of them. I don't know if it would just trim off some of the mass killings, or half of them, or all of them, but it would definitely have an effect.
I wonder if a world leader were to suggest love, what would be the reaction? Would he or she be ridiculed? Laughed at? Or, might people actually acknowledge he or she was right?
And, could you persuade people so easily to start loving each other more? I don't know, but the first step is to suggest it, to ask for it. Nothing taught is nothing learned. If no one suggests love is an answer, there is not much chance we will move that direction.