No Skin Mobility

No skin mobility; Scarring

Below: This photograph shows the lack of skin mobility during erection of a circumcised penis. Note the dark scar where the foreskin was amputated.

This tightness and the unnatural dryness of the penile shaft and head causes some men (and their partners) pain, abrasion, and bleeding during sex. Breaks in the skin are an effective way to transmit and contract sexually transmitted diseases, including HIV

Below: These five photographs show how the shaft skin of
an intact (non-circumcised) penis moves during sexual activity.

Anonymous photo taken from usenet news.

Range of skin movement marked by point A is several inches back and forth.
Note how point B moves and the end of the foreskin widens to accommodate
the head of the penis. Notice the smooth texture of the head of the penis.
The moist mucosal surface of the foreskin and glans is similar to that
of the female labia and vagina.

Personally
Until i started restoring i had mo idea the skin could be mobile (slide freely on the Shaft)
it was only after 6 months i discovered the skin slid smoothly if only a little on the shaft and now after a year restoring the difference is massively obvious and i refer to it as "the Glide" .

"The Glide" alone is Reason to restore in my opinion
For Example "during masturbation the enjoyable feeling of a thin layer of skin gliding back and forth over the veiny shaft and rather than my hand rubbing against the frenum and head the exquisite feel of the "Foreskin" bunching and rolling over the head is personally preferable by a long margin"