Am I wrong about this?
As we ride more and drive less, I'm thinking everyone carries a favorite pannier or backpack. Personally I have both. I use a backpack when my bike doesn't have a rack, but I really prefer to travel with a pannier.
I commute with one every day and am in a strange ritual of packing it every morning with clothing, food (for lunch..) and other things.
Even though it slows me down on weekend rides (the drag is noticeable too...), I often bring one without much in it. Then as I return, I'll stop at a shop on the way and fill it up.
My pannier is almost part of my uniform. Some of my friends tease me that it's my purse...