This is a good set of questions, but I do have an answer. The pleasurable thing about experiencing stamps or coins is not the sending or spending, but the design or rarity; purely aesthetic in a way divorced from the original purpose of the article. Plus, if you use a stamp or coin, you have to give it up. However, a vintage bike worth it's salt was designed to go fast, feel good and be an exciting experience for those reasons. If you hang it up and don't ride it, that's denying more than half what it's about, IMO. Same goes for any made object whose purpose was performance -- automobile, firearm, shoe, etc. I don't get why people would never use them, unless they're just not competent to have that aspect of the experience.