The common life is integral to many forms of religious life. It is certainly the foundation of almost all Franciscan life. So why bother to live closely with other people?
If you listen to the preachers of sunshine you might think it was just for mutual support and personal intimacy needs. These are part of what religious community is about, but I don't think they are the main thing.
If you live closely with other people you quickly realize how unreasonable and idiosyncratic they are. If you pay attention to their reactions to you, you will soon notice that they have drawn the same conclusion about you. Thus you can find in the common life an opportunity to give up your (unreasonable) expectation that others should be perfect in their work and interactions. And you can also realize how much pettiness and irrationality they have forgiven you.
Thus the common life can be a powerful school of humility.
How we interpret the words and actions of others becomes critical. Do we hold them to every little claim they make? Do we demand that everything about their lives be coherent? Here one hermeneutical rule that has helped me greatly is Hanlon's Razor. It says, "do not attribute to malice that which is adequately explained by stupidity." Put somewhat more delicately, if a moral judgment is not necessary to explain what you observe about your sister or brother, why bother with it?