To me I think that it has mostly to do with clothing. Shoes, shorts, helmet - also, how am I going to carry my wallet?
I sometimes yearn for the days when I'd just jump on my bike in whatever clothes I happened to be wearing. My beater bike has double sided pedals so I can ride it comfortably without cleated shoes but Mrs. Grouch yells at me when she catches me riding to the hardware store without a helmet.