I never quite realized how charged an issue this is. It seems to be taken a bit to extremes though.
It's odd that people never say that about shaved faces.
Imagine how demeaning it would be to describe every man who shaved his face as looking like a pre-pubescent. And yet with genital shaving it's bantered about as being quite normal ...
I've worn a full beard or thick goatee for over 15 years and wore one off and on for the 10 years before that. A number of people have said things like "You would look so much younger if you shaved that beard." Or "the beard makes you look so much older than you are."
I don't have a baby face by any means, but when I did shave it a number of years ago acquaintances and colleagues did say "you look so much younger" and meant it as a compliment I'm sure. Most of the people very close to me wanted me to grow it back, I think they missed it mostly because it was so familiar to them. My sister even said "you look sinister without a beard". That comment actually kept me shaving for a while.
Many guys will grow a beard to look more mature. Of course many more grow one to be rebellious too. So there is some slight element of maintaining the youthfulness of preadolescence in a man keeping his face clean shaven. The fact that facial hair is by its nature a more public expression than pubic hair, it's existence or non-existence will naturally be less taboo.
Just as facial hair styles are seen as rebellion when they buck the standing norm, so are choices about pubic hair styles.
In holding to my statements above, I can't understand how it can be viewed that a shaven pubic region does not look at least somewhat more childlike than one with a bushy mound.
Another point harkens to some baggage I carry from the era when I grew up. In the eighties in the conservative American Midwest, my young adult contemporaries generally sported full manes of pubic hair. We could be certain that our parents did too. It seemed so staunchly accepted as the societal norm. To come across a girl that shaved around her vagina at all was a rare find, and something quite racy. A girl that took that much time and care grooming her genitals was often viewed as "easy" or "a bit of a nympho." Mind you, many of us young bucks were trying to talk our girlfriends into shaving their pussies. It was exciting and different.
I respect everyone's choices and preferences. Personally though I prefer a full coif on both sexes. But especially on men. When I see a fully shaven adult penis I can't help but think it looks just the slightest bit silly because of the incongruity of the absence of pubic hair next to the mature genitalia.
Don't get me wrong. I love seeing penises and vaginas anyway they come, shaven, au natural, and any point in between.
Variety is the spice of life.