With restrictions on garage space being a limiting factor, it tends to colour my prospective over what is worth keeping. Secondly, if something has been fully enjoyed, driven and shared some great memories of past journeys and some great life experiences, I can understand just keeping it there as a reminder of past times.
Whilst each to their own, I don't see the point of owning something and then not using it because the very essence of its attraction to you in the first place eg low mileage is the very thing that stops you enjoying it more fully. Cars were designed to be driven, and sometimes we get a little too precious with them.
You are right of course. A pal owns a Ferrari 360 than now has more than 150k on the clock and is a daily driver. Used like that its very reliable - Ferrari engines are way better than recent Porche and the ally bodywork seems to last well. Car isnt worth much of course but so what? I definitely got it wrong mileage wise.