I chuckled a bit at the OP's open-ended warning because there's a Commander based semi-permanently at my home field here in West Oz. If the owner waited for the cross-wind to subside below 12 kt, he might never get it on the ground, especially this time of year.
Can't add anything to the correct comments regarding formal x/w certification but one practical point is that, not infrequently, high winds come with large guests which can influence how well an average pilot can handle the aircraft. When I was learning to fly, a steady x/w was not a particular challenge; keeping on top of the gusts is what required practice. Nowadays, I notice this effect with many PPLs and recreational pilots, especially those who fly infrequently. So, in a practical sense, a modest x/w specification may go some way to protecting pilots from themselves.
I do think there is considerable variation in the amount of optimism shown by manufacturers. For example, there's no discernable difference between what one can do in a C150 vs a P2002. In the latter case, though, Tecnam have a book value of 22kt x/w. The aircraft indeed handles well to beyond this limit but, especially with the no differential braking versions, landing with a strong left cross-wind will require nosewheel steering to become rapidly active if the weeds are to be avoided. The experience of having the touchdown speeds exactly right, anticipating reaching the limit of right rudder authority, and being ready with the central brakes is all part of learning about the aeroplane. From a manufacturer's viewpoint, it'd probably easier to just write '12 kt limit'. But I'm glad they didn't.
Last edited by tecman; 6th Feb 2013 at 06:10.