6 million years of primate evolution have led us to a penis with a foreskin.
Then a few thousand years ago, some guys who bathed themselves who knows how often, decided that they should mutilate babies thus making them identifiable to their particular tribe.
No animal on earth has an exposed penis.
If it were inherently important that the male penis be exposed, nature would have taken care of it. I will trust natural selection on this one rather than some smelly unhygienic desert nomads.