Why are so many superheroes clean-shaven?

Superman / Clark Kent – NO beard

Batman / Bruce Wayne – NO

Robin – NO

Green Hornet – NO

Kato – NO

Blank Panther – maybe, hard to be sure

Any-Man – NO

Aquaman – NO

Captain America – NO

Conan the Barbarian – NO

daredevil – NO

Green Lantern – NO

Incredible Hulk – NO

Iron man – hard to tell, but doubtful

Spiderman – NO

Wolverine -> YES but short cropped

Why are so few hypermasculine superheroes non-bearded?