Also, people launching art projects, participating in active art communities, etc. have generally better "people skills" that introverts who prefer to spend the weekend at home doing technical side projects (like me!).

This is a highly valuable work skill for a technical worker if he/she has the need to work with clients, present updates or discuss requirements, much more than having a few small GitHub repos. By focusing in side projects you can be filtering out these skills in your workforce.