I have seen many events that would have NO racing going on under those rules. And folks come from a long way to these events.., to go home without a race at all would be terrible.
And even in dice-throwing winds, it seems the top sailors always still manage to do well.

By using those types of guidelines for the RC, you can easily paint yourself into a corner. A couple of years ago I was PRO for the Tornado Nationals (I think that was what they were) in Biscayne Bay.
The wind started out pretty decently and I set a weather mark at around 1.25 miles, but the wind dropped off to just above the miniumum of 5 knots. We were constantly taking readings to insure we stuck to the rules.
In order to make the race stick, I shortened the next weather mark to around 1/2 mile. The first boat rounded the weather mark and made the finish line when the air totally dropped to under the minimum.
Under their rules guidelines I could not abandon the race at that point -- we already had a finisher. And there was now a time limit for the rest of the boats.
Typical of the class, most of the fleet asked for redress. I appeared in a hearing before a jury and explained that I would have loved to abandoned the race, but the class rules themselves made it impossible for me to do so. The jury ruled in favor of keeping the race.
I conducted the race exactly to the classes standards.., and they were all ticked off about it.
Sorry, I did not write the rules, just lived by them.

Now, this is exactly what you can get yourself into.., and it is not a pretty picture. Best bet is to be sure you have a PRO that will use his/her own discretion and make good decisions so everyone is happy.

Rick