If you normally wear some sort of baggy sorts they will act like small parachutes on your thighs. Also the snug fit of the lycra reduces chaffing of your thighs if you are prone to that. The pad is particularly nice if your out for more than 10 miles on a ride.

edit: Oh, and the occasional hoot from a carload of young ladies is always a nice stroke to the ego for this 45 year old family man.