I suspect it is because they never tried it. My own experience is that:

  1. armpits stink much less (I suspect that the bacteria have less real estate).
  2. The pubic area is more sensitive if it is not covered with hair.
  3. As for the chest, it is matter of taste :-)
  4. Legs take, as observed above, a looong time. But, shaved legs feel ever so nice, at least for the first days. The main danger is getting distracted by the texture of your trousers.

Now, what is really boring is shaving around a beard. Boring boring boring, and can't be done in the shower because you need a mirror, and mirrors fog, and only a turbogeek would buy a no-fog mirror from the Sharper Image catalog.