My qualified guess is that because of the fact that gusts are very hard to predict, there is such tolerance to keep the meteorologists back free...
When gusts are reported, one should allways keep in mind that it may get much worse than forcast. And this is also explains further why one should "interpret" the TAF and not just read it and use it s the plain truth.
nother exmple is the T/Td. If they are the sme value, but no fog is forcast, that should ring a bell.
/LnS