When I was half way through my first cycle... I went to the grocery store to get a sandwich. I set the sandwich down on the counter in front of the hottest looking checker I'd ever seen. I was just at the point my muscles were starting to bust out everywhere... up 15 lbs. She took in the arms... the chest... the shoulders... looked me in the eye... she smiled evil and said, "Wanna go out after I get off work?"
So to answer your quetion - NO... you don't need them... but for chicks like her it sure helped.