From a medical perspective, I'd worry that many of these folks suffer from major depressive disorder, social anxiety disorder, or obsessive compulsive disorder.

This is not to pathologize behaviors people choose which don't interfere with quality of life, but my gut reaction is that many of those described in the article would benefit from treatment with psychotherapy and/or medication. However, I'm told that significant stigma is attached to seeking evaluation and treatment for such issues in Japan (and obviously elsewhere, including the west).