I think that mental illness has always existed to some degree but I'm not sure that it is more common in today's society or not simply because human population is many times bigger than it was in ancient times which means there is a higher probability for more people to have a type of illness and also because there was less technology and less knowledge about the human mind 100+ years ago which means that many cases of mental illness likely went undetected and undocumented.

I think that the primary difference between ancient times and modern times is how mental illness was dealt with. In ancient times, people with mental illnesses involving delusions were typically regarded as Shamans or spiritual leaders who were valued members of society because of their seemingly prophetic ability to communicate with the gods of ancient times whereas somebody with a mood or personality disorder was typically outcast or treated like a monster for their illnesses due to lack of knowledge about the inner workings of the human brain and mental illness in general.

Furthermore, I think individualism is important first and foremost because without the individual, the group cannot exist and if the individual is hurting or isn't happy, those he or she relies on hurt too. Community is important but is secondary and complimentary to the individual I think.

Finally, I think a big issue with society is the need for all but the most driven and ambitious or lucky individuals to need to work long boring menial jobs to survive. I think humans are more than a hunter-gather species by nature, but a species evolved to think, innovate, and follow their passions.