If you fly in conditions like that the risk of an accident is far greater. If lots of people fly in those conditions eventually someone will have a prang, either because he is in the wrong place at the wrong time or his skill level is exceeded.
Then an inquiry is held and questions are asked regarding whether it's a good idea to operate in conditions which come close to and can easily exceed design limits. Obvious and safe conclusion is no, and restrictions are put in place.
A year or two ago we were bashing Cebu Pacific for doing the same thing. If Cathay with their experience of typhoons/hurricanes/cyclones think it's a good idea to sit it out then it probably is.