Hi Jerry,
I think it can be very healthy. A place that one has to oneself for whatever he or she wants. Since so much time in a marriage is spent together- at night, dinner, breakfast, weekends, seems a spot in one's home to be alone is very healthy.
Now, both should get one equally.
May also depend what one does in it....playing violent video games nonstop may not be as healthy as having a bunch of plants to water and tend to...or photos of nature around the room, or surfing...or an alter....or whatever brings peace...
cultures are different...some would not see a need for seperate space I am sure.
But then again, in some of these cultures , it may be that alone time can be easily found outdoors in the jungle or wilderness or wherever one is in nature... perhaps.
I like my alone time, so I chimed in..")
Its a short term retreat from the real world. Women do it with their sappy chickflicks, men do it more in a physically form. It is the one room that is 'his' as opposed to the house which is 'hers'. As for "Hart" and his idea, sounds like he is projecting his use of his mancave for anger management onto everyone....tsk tsk.