It is of practical value in determining length of exposure and amount of protection.
Makes sense to me.
I sure don't have to worry about wind chill factors where I live but professionals such as mountaineers and arctic expeditionists, use and apply wind chill factors in there gear selection all the time. It must be a valid and scientific way judging the potential deadliness in exposure otherwise they wouldn't use or refer to it.
Regardless of what wind protection I'm wearing while hunting in the mountians it's always far more difficult to stay comfortable when the wind is gusting. As soon as the wind stops or I can shelter myself against it, instantly I feel warmer and more comfortable.