"Not so much" at the end of a sentence

The phrase is meant to be dismissive and is a somewhat current catch-phrase that has been used comedically by some television celebraties in the US. While looking for the source of this expression (one of which cited the origin as the "Brady Bunch", a highly popular and iconic sit-com from the 1970's), I came across this excellent article by Daniel Weiss from the Columbia News Service - the gist of which is that unlike other catch-phrases that have a brief moment in the spotlight such as "Been there, done that" and "yada-yada-yada", "not so much" has a certain style of being dismissive without being downright rude. It was compared to fashion in that one can put it on (i.e., use the phrase) to come across as humorous/dismissive.