Reminds me of how 'The Real World' TV show started out as a whole bunch of different people living together in SF then as the show progressed season after season it just became a 20 something mono culture.
Actually, 'The Real World' changed cities every year and the original one was in Soho, NYC, only Seasons 3 and 29 were in SF. </pedant>
(Sorry, couldn't help myself, but you do make a good point)
its a shame. We all can benefit from more community. I think we can also benefit from diversity of ages etc, wisdom passed down/up etc.
Maybe as they develop and become bigger... But kids out of uni are more or less still 'getting away' from the adults. And empty-nesters probably would have a different tolerance for noise and active hours.
Some of it has to do with the people who would be interested in an arrangement like this. I saw nothing about couples, for example.