Over the years, I have seen no evidence that having a longer shot clock increases the level of play. All a longer shot clock brings is slow play.
Two of the slowest players of the modern era are Ralf Souquet and Eklent Kaci. When they play off the shot clock, they take forever and play well. When they play on the shot clock, they play just as well. This week, Kledio Kaci, another notoriously slow player, played the best pool he has ever played and the thirty-second shot clock was in use.
The intuitive argument that if decisions at the pool table are made more slowly, those decisions will be better, does not hold up to scrutiny.
The players, as a group, have proven over and over that they can make accurate decisions quickly, but give them forever to shoot and that's exactly how long they will take.