Think about it ... the three-point shot, the two-second rule, the elimination of jump balls, etc.
Exactly.
Those rules were adopted to create a more open game, with more passing, player movement, penetration, and pick-and-rolls/pick-and-pops. Watching a big man back down a defensive player, while the other four players stood around and watched, was boring beyond words.
It worked. Now, the Warriors are the model offense, with continual movement, tons of penetration, unbelievably accurate shooting, and forced defensive switches.
The sky hook has far less value today. It doesn’t add to the flow of an offense - it replaces that flow. Offenses today (especially when there are so many 35%+ 3-point shooters out there), don’t need a move that invariably stops movement. Even if it is an acceptably efficient move, it is only 2 points, and it makes everyone else less efficient.
Big men today are concentrating at learning the pick-and-roll/pop, or developing into a spot up 3-point shooter. Failing that, teams look for defensive specialists, quick low post moves, or offensive rebounding.