Tattoos do seem to wax and wane in popularity - the big difference in the last 30 years seems to be that they have become gender neutral - used to be a much higher percentage of men than women with any tats and more particularly with extensive tattooing.
I do think the more permanent nature of tattoos vs. body piercings creates more 'regret' through the years. And there is quite a vibrant business in tattoo removal that, as techniques have improved, has grown very profitable. What appeals to a 20 year old with a ripped body, can become less appealing on the expanding flesh of a 50 year old! And some matters that were vital in youth, become trivial in time.
And appearances do matter to us all - we make lots of snap judgements about people we meet based on visual cues - the longer the contact with a person gets, the less important those initial impressions become, but they are real. If you meet your new doctor and they have L O V E and H A T E tattooed on their fingers, you may change doctors pretty quickly regardless of the diplomas on the wall.
Personally, I have always thought regardless of gender, choosing body art in locations where the choice to display/conceal was an option depending on circumstance made a whole lot of sense - like any fashion/accessory being able to change the effect depending on the occasion seems sensible. But I guess for some people the art is so integral to their sense of identity that it becomes important to display it at all times.