This modest rule change wouldn't make the game significantly less entertaining. Runty point guards, denied the opportunity to turn routine layups into riskier sky-jams, might sulk, but scoring would increase. Missed layups are often tipped in by a trailer; missed slam dunks are not. And, trust me, there would still be breakaway dunks, although more of the sure, two-handed variety. If you want to see this shot, watch Kareem Abdul-Jabbar. He has been using it to great effect for years.
Referees with whistles and a simple new rule—that's all we need to ground basketball's airborne show-offs, but not its airborne show.