All of us have a rougher texture to our skin towards the base of it. I don't think it has anything to do with the potential for gains, although it may be a sign that you have made gains. Circumcision may have caused some of your pubic area skin to be pulled up the shaft too to accomodate your growing penis during puberty. Do you have hair growing up the shaft? Unless you have some kind of sexual dysfunction or discomfort, it is nothing to worry about. It is a popular misconception that the entire penis is supposed to be sensitive. Actually, all the nerves and structures for sex is at the tip, near the glans. The skin at the base is just skin, no more sensitive than any other part of the body. That's why circumcision is so damaging. Almost all the sexual structures of the penis is removed, leaving only the glans and MAYBE if you're lucky, the frenelum and a little inner mucosal tissue. Want to have better sex? Don't worry about the base. Baby the end of your penis. Wear briefs to reduce irritation to the glans from rubbing, keep the head and inner mucosal remnant (the light colored skin above the c-scar) clean and apply lotion to both every day to keep them moist and supple and highly sensitive. Jelqing also helps, as blood is forced down into the tip, improving circulation there and sensitivity.