you're right, but when designing and making car parts such as brakes and bearings, weight or efficiency are not all that important. i certainly wouldn't want to rid a bike where a
large chunk of it's efficiency was lost to
extreme longevity, although i have parts on bikes that are decades old and still work fine, perhaps it's the demand for ever lighter components that you're all suffering from?
according to sheldon, a well maintained english 3 speed would outlast us all. they do come with a cost of being a couple of kilos heavier than perhaps the bikes now available, but then there's only a few of us that aren't a kilo or two too much anyhow