I'm not saying that no one would build their own home theatre or restaurant sized kitchen. But a lot of people honestly wouldn't bother if they had other options in their community. It moves the cost/benefit curve over by a standard deviation or two.

I think you are advocating for trying to make the experience of apartment living less shit, based on some idea that density is inherently good. However there is no example where this is the case, as less density always allows individuals more control over their immediate environment. I don't believe people choose community options deliberately, people who use them simply have no alternative. There is no positive evaluation being done, or cost/benifit it's simply the only affordable option.