As a 6'3" 240 pound mountain biker who has recently taken up cycling on the pavement, I was very resistant to the idea of wearing lycra. Partly because of appearance, all of my extra weight is between my neck and my waist, but also because I did not want people to think I was some Tour De France wannabe. I also did not know much about the benefits other than aerodynamics.
Well, I let my LBS owner talk me into taking one ride, and it was fantastic! I can only compare the feeling to skinny dipping. I was cooler and more comfortable. I just feel sorry for my neighbors as they are the ones that have to see me off the bike.