"There's an indisputable fact that circumcision removes about 12 square inches of highly erogenous tissue on a [male] adult. It's obvious, if they're missing tissue of the penile shaft, anyone with common sense would agree that they're feeling less pleasure, because they don't have the thousands of nerve endings that went with the tissue that was thrown away.
Plus, the foreskin has various functions including being a removable 'sleeve.' The sleeve slides up and down the penile shaft, reduces friction and stimulates the glands and the head of the penis and it makes it more comfortable and pleasurable for his sexual partner."