I think using some minimum wind speed in the NOR is a selling point for a regatta. At my yacht club, ABYC, it is rare that a race sees less than 5mph on the course. Any decision to require a minimum wind speed would have to be determined based on the location though. Some lake venues may not have wind consistent enough to count on any wind much less determine a minimum. Most coastal areas could plan on some minimum.

At our area J's we waited two hours on the water for wind high enough to sail. There happened to be a high pressure system that eventually allowed racing to happen. No one on the water complained.

Dan