Everyone knows the primary reason for the hobby is sex, as good as we can get it, but there are other aspects, more than just ancillary benefits, that become obvious as we get older.  So, I'd like LG's and others' views on these.  
For me, the hobby provides measurable benefits that become more important as I get older -- I'm in my late 60s.  Years earlier, my only interest was sex, the hotter the better.  
A few years ago for no apparent reason I developed high blood pressure that didn't look good.  My doc prescribed medicine, and all was well.  In addition, even without medicine a visit to an AMP brought normalcy that lasted a few days, as did a soothing non-sexual massage at an upscale spa.  The only difference was that the AMP experience brought more serenity and the feeling of well-being lasted a bit longer.
With the doc's approval, I skipped the pills, but massages/hobby alone were insufficient.    
My wife and I live an urban life style -- not wealthy but comfortable, good jobs (she full time, me part time) kids fully grown and established, good friends, cultural and recreational activities, good community, etc.  No demonstrable upsets and we are very companionable outside of sex.  She'd like more affection, not necessarily sex, and I depend on the hobby to fill what would be a big void in my life.  
In noticeable cycles, I experience a buildup in tension that goes for about 10 days, regardless of outside circumstances.  At the end of that period, I'm more inclined to be snappish, more aggressive in conversation, impatient, and jumpy, although I'm generally condidered easy going.  This is not a polar or manic situation.
Recently, I saw a provider I'm very fond of, and booked extra time because she's been working in another city.  After the festivities, our catchup conversation was affectionate, laced with laughter, and her interesting insights on life outside the hobby.  The time flew by.
Later, I felt serenely relaxed, pleasantly fatigued.  That night I slept 8 hours straight through, and my BP was the lowest in months, well below recommended standards.  Although my daily life is happy, that morning I felt serenely content.    
Have there been any reliable studies of the effect of the hobby on participants?  Beyond the impact of sex, that is.  On health, feelings of well being, overall behanior, etc.  I could make a good case that the hobby occupies a unique niche like no other in stimulating positive human behavior and well being, based on  overwhelming anecdotal evidence alone.  And the impact of a great hobby experience is different, and often better than, sex with your wife or SO, going to an AMP or spa, attending a transcendental cultural event, or watching a playoff game with the guys.    
I know respectable older guys who pinch ladies' bottoms and make obnoxious sexual remarks, clearly because they are frustrated.  I know respectable older women who yearn for dancing partners with whom they can have something different than their companionship with non-dancing husbands.  Whether they want something more than dancing, I don't know, but if they do there should be some kind of hobby for women as well.  
Bottom line: we'll never get health insurance for the hobby, but it should be de-criminalized and  sex workers need protection from abuse and exploitation.  Health protection and security for sex workers and hobbyists could also be improved.  Difficult, but not impossible. Reactions? Apologies for the length.