With God's love and forgiveness a given to believers, I believe love of self is directly connected to forgiveness, which is directly connected to loving others. Self-forgiveness. We are unable to forgive ourselves for our own sins, and carry that over to others. We can't forgive others because we can't love them. We can't love them because we can't forgive ourselves. They may not seem connected, but I believe Jesus connects it with his command to love our neighbor as ourselves. We can't love ourselves unless/until we forgive ourselves. Forgiveness is simply letting go of past sins that we drag around with us.
There was an excellent film about the baggage we carry and the effect it has on our lives, I think it was called "The Mission," with Robert DiNero and Jeremy Irons. Highly recommend it.
As for why people feel unloved, a quick run-through of some of these threads would give a good glimpse. This is the picture of Christ we present to the world via cyberspace. We don't act very loving. People feel unaccepted, rejected, never measuring up, never good enough, not perfect enough. When we love ourselves, we are less hypercritical, less cynical, less angry, more patient, more tolerant (Scripture says to "put up with each other"), more loving.
"Love your neighbor" isn't the most important part of Jesus' words. It's "as you love yourself."