This is a topic which has interested me for many years, ever since making some observations in my own studio over the years. In my own case my typical boudoir client would be a woman within 10 years of 40 (on either side). Many of them had undergone a life changing event, either being dumped by a long time spouse or getting rid of an emotionally abusive spouse, or maybe recovering from a life threatening illness. Others simply recognized approaching middle age and wanted photos "before it all falls apart".
Now understand, these were not models, with most of them never before having had serious photos made. Most had some sort of bodily flaws, some minor, some pretty damned major, ranging from stretch marks to large surgical scars. What many of these ladies had in common was the wish (need?) to affirm that they were still attractive, sensual and vibrant women. Many, if not most, had awful self image;they had simply given up or were at the point of doing so.
The above article indicates this is some sort of therapy and I believe that to be accurate. But the photographer is not the therapist! Instead it's a form of self therapy and the photographer is simply a tool in that therapy. But that does not mean the photographer is unimportant. A good photographer can boost a woman's self image and help her to gain a great deal of confidence in herself But a shooter who is unmotivated, just going through the motions or lacks ability can do the woman going through this a great deal of harm.
Shooting well is a debt we owe these women just because we have the ability to do what we do.
Part of my collection of about 5000 images I call Standing Naked, The Sensual American Woman can be seen on my web site, http://www.distinctiveimages.com