I don't know about you but when I draw undraped models I'm always shocked by the drama and profundity of the body. The human machine is awesome. Layer over that the nuances of intellect and personality and you have a very appealing subject to draw.
The problem is that it's too appealing. If you're like me, no matter how much you may have resolved to caricature the model (whole-body caricature) , the moment you see her all you can think to do is to revert to stark realism. Anything else seems unfit for the importance of the subject. This is why you have to double your resolve to caricature. If you have trouble doing this then you should pose the model draped for half the session.
Another problem is that realistic life drawing encourages scratchy lines. Realists tend to search for the forms with lots of tentative strokes til they get what they want. Cartooning isn't like that. A cartoonist needs to learn strong, confident lines.
Some cartoonists put their best effort into realistic life drawing because they're frustrated with the way their cartoons are turning out. Life drawing becomes a sort of holding pattern where they concentrate on general draughtsmanship for a while while the rest of their life sorts itself out. That's OK if the rest of their life does get sorted out but what if it doesn't? They can stall for so long that life drawing becomes the only skill they really have.