I shave it all because I love the way I feel and look. Other guys look incredibly sexy shaved and groomed also.
Some dudes think it's too much work, but add up how much time you spend getting haircuts and worrying about how your hair looks all day everyday. The price of haircuts, product, etc is outrageous and handsome guys with great bone structure look awesome.
I also do my whole bod because I feel so sexy smooth and my various underwear and gear fetishes feel so much hotter when silky smooth.