I'm really glad you raised this.
I was looking at the website of our local life art class and they have hundreds of examples of students' work.  It was a joy to look at.
Doesn't answer the question but a glance through their website shows the sheer variety of interpretation of the human form.
http://www.stroudlifedrawing.com/
I've modelled for other groups and it's really interesting and a vanity to see how others interpret you.

This sounds quite unusual. I have been going to life classes in the Stroud area for many years and have only seen any inhibitions about drawing the full figure once, when a couple of male A level students got nervous of a male model and only drew his portrait. Otherwise no one seems to have any hangups about what they draw. The models are roughly 50/50 male/female, and the students are predominantly female. I've been to the Stroud drop in sessions, which are very good, but I'm going to tutored sessions in Cirencester at the moment.

It really is a gift to be able to draw
Or paint.what ever the subject .
Its quiet astonishing how some of these
Artist mange to create such amazing
Works .
How ever the artist interpret the subject .
Good luck to everyone .
Best wishes .
Pete.

I have worked for some years as a male life model,and have enjoyed the experiences of seeing the artists representations. Although some try to capture the pose and the whole body, other are quite a few who only concentrate on certain parts such as the face,hands or torso. I would agree that the majority only draw the genitalia in a sketchy fashion even when detailing the rest of the body and underlying musculature, quite often just making the area a shadow rather than drawing the anatomy. If I am happy to pose nude then I see no reason for the artists not to study and draw all of me.

I now think that the artists show their work to their families and others who are prudish types and don't want to see genitalia. Most of them do not sell these drawings but they may exhibit them.

Yes, the genitalia is sketchy, incomplete on purpose.

I now think that the artists show their work to their families and others who are prudish types and don't want to see genitalia. Most of them do not sell these drawings but they may exhibit them.

Yes, the genitalia is sketchy, incomplete on purpose.

I have never been much of a painter and I have never been to such a class, but a friend of mine used to study art in our national art academy and she has been showing me some of her paintings during that period. All the models that she painted had their genitalia sketched in details. I also have another friend who is an amateur artist and draws naked bodies as a hobby and he also always has the genitalia done in details. This topic is actually the first time I've heard that some artists avoid drawing the models' genitals in detail, I never really realized that such a problem could exist.

The reason for that might be simpler than it sounds. While I’m sure some students don’t draw genitalia because they’re embarrassed, most just don’t have the time. In figure drawing, the focus is on the full body of the model, and you’re observing everything there is. Muscles and structure of the body are the most important thing to learn, not the small details.
I myself attend figure drawing regularly, but I often don’t get around to doing the genitalia, as I’m typically spending more time on some part of the body that I need to get better at drawing.
In short, people don’t draw every part of the body because they simply don’t find it useful to learn.

I agree with the last correspondent, you will often notice that hands and feet are often also neglected, since they are quite complicated, and the artists time is taken in representation of the whole body shape. I write this as both an artist  and a model.

The reason for that might be simpler than it sounds. While I’m sure some students don’t draw genitalia because they’re embarrassed, most just don’t have the time. In figure drawing, the focus is on the full body of the model, and you’re observing everything there is. Muscles and structure of the body are the most important thing to learn, not the small details.
I myself attend figure drawing regularly, but I often don’t get around to doing the genitalia, as I’m typically spending more time on some part of the body that I need to get better at drawing.
In short, people don’t draw every part of the body because they simply don’t find it useful to learn.

I was once posing for a class and as usual liked to look at the students work.  One gentleman had basically drawn a stick person attached to an anatomically excellent, highly accurate if somewhat enlarged version of my member.
Didn't know what to say really! 

All the drawings I saw of myself recently included my genitals but there was wide variation in how they were represented. Some were detailed, some were outlines, some were flattering, one depicted them in heavy black pencil with the rest of me was drawn with delicate fine lines. I guess it depends on the artists style and interpretation.