[Jorge]

A circumcised male that has his exposed head constantly rubbing against his clothing looses a significant ammount of it's sensation.

Who told you this?
Guess unshielded finger tips must lose their ability to feel too.
I don't think so. Rubbing off dead outer layers of skin would increase sensitivity if anything.

[Age of Reason]

Guess unshielded finger tips must lose their ability to feel too.

Fingertips--unlike the glans of the penis--were designed by nature to be always exposed.

I wonder how your eyes would get along without eyelids.