I'm in partial support of Sunfish on this. This is a complex subject which goes far beyond simple structural engineering discussions and involves judgements within the whole basis of the actual regulations themselves, of how much, how often compared to all the other competing risks to flight.
Most of the preceeding discussion are of a brevity that leads for lots of misunderstanding between posters.
In my opinion, you really can't do justice to a reasoned discussion simply using a keyboard driven forum.
I don't mean to abort this discussion but only to caution against simple conclusions for or against since clearly all the facts (rule intent and design intent) are not in evidence.