My philosophy is bikes that were icons of their era, for example, raced in TDF etc. or were worthy of doing so, should be preserved as much as possible (while being made available for viewing) and ridden minimally, if at all. Less rare, more utilitarian bikes should be enjoyed in whatever way their owners' see fit, whether preserved, restored, displayed, modded, ridden etc. I prefer to mod the wear items on my vintage bikes (this really just boils down to chainrings and freewheels, which I like to mod anyway to optimize gearing - tires, tape, brake pads & cables don't really count since these are normally replaced already during a bike's first working life) , and keep the original parts for possible restoration to original.
Derailleurs and rims are a grey area - very high utilization may wear these out, but that is the owner's prerogative. I have a set of "workhorse" wheels for my Motobecane, to reduce wear & tear on the originals.