The sky hook is a largely antiquated shot because of the way the game has changed in how defense is taught and officiated. If the same lower body contact open players existed when Kareem played as exists now his sky hook would be a much rarer weapon or he never would have developed it at all. The brilliance of the sky hook is that it is a unblockable shot by a center, but the shot is rather easily disrupted by contact when shooting, particularly the lower body contact and subtle pushes when a player is shooting that all post defenders now use and is allowed by current officiating.
Kareem developed and played at a time when there was a premium placed on being able to shoot over defenders because every shot was worth two points so a player had to be shoot over defenders if they were going to get closer to the basket. This is why just about every player as recently the 1980's had a high release point on their jump shot, and many brought the ball behind their head. If a player tried to back down their defender physically he was going to be surrounded because there was no 3-point shot to guard against. The post player wanted to take his shot 10 feet from the basket, not kick out for 20 foot shot worth the same amount of points.
With the 3-point shot offensive post players began to physically back down their defenders as they now had space to work with as defenders now had to protect the 3=point line. You had people like Charles Barkley starting in the late 80's, but eventually you had Shaq who would run over people in the post while he was surrounded by 3-4 3-point shooters. As a response defenders had to body up much more with their lower body and officials let contact body contact go even while a player was in a shooting motion. Contact that would affect the sky hook, and why you really only see the jump hook now which is a quicker action from a much stronger base that minimizes the effect of body contact. If you go back and watch the film you never see even Wilt back people down and go through people, and you don't see the physical account by defenders once a post player catches the ball. Where now every post defender is taught to body up.