The useful thing about communities is that they can give rise to shared values and a consensus view of reality. This is also the dangerous thing about them: communities under stress can produce really scary norms and values (Jonestown, Nazi Germany, Cambodia under Pol Pot, etc). So we need individuals to balance this out sometimes, and produce new paradigms (it's a bit like Kuhn's theory of scientific advances). Examples of such individuals triggering paradigm shifts include the founders of religions and great collective surges of conscience (early Unitarians, Gandhi, Martin Luther King, early feminists, etc.)
But assuming for the moment that a community is going to tend towards sanity... whom should a community include? If it is going to call itself a community, should it exclude the "walking wounded"? If its collective values are strong enough, can't it include (and help to heal) the damaged people? OK, some people are too damaged and need professional help, but we ought to be able to help the "walking wounded".
How do we create and nurture community? By meeting regularly in large and small groups; sharing our feelings and thoughts. By discussing and negotiating our shared values. And by developing collective ways of putting those shared values into practice.
I've just been reading On Forgiveness: how can we forgive the unforgivable? by Richard Holloway. In it, he talks about the radical change that can be brought about by forgiveness (for example, the Truth and Reconciliation Commission in South Africa). Forgiveness is one of the practices that a community needs if it is going to function effectively. It is not something that can be done lightly; it's not about just forgetting what has been done. It is a radical act, and not one that you can command people to do - but it can be developed as a spiritual practice. Another important factor in the development of community is compassion (for ourselves as well as others, and for all living things, not just humans). Compassion can include empathy, love, pity, and mercy. And finally, a certain amount of humility might be useful. Humility literally means "closeness to the Earth". By humility I mean a willingness to accept our own shortcomings. "Let he who is without sin cast the first stone." I do not mean that we should only focus on our shortcomings; compassion requires that we and the community should also celebrate our strengths; and if the community celebrates our strengths, it can also benefit from them.