I don't see it as an age/pubescent (pre or post) thing at all. For me it boils down to 2 things: 1. I'm used to it now due to its prevalence in my generation, and so some level of grooming has become as expected as smooth legs and underarms. 2. As a man with an oral enthusiasm, it is generally a more pleasant experience on both ends if some of the brush is cleared away. Including on an olfactory level, since hair tends to hold on to odors more readily than skin alone. Mind you my enthusiasm is rarely lessened by the presence or even abundance of hair, it is merely a preference.