Great article. The underlying reasons that some in the workplace may frown upon the personal projects and hobbies of their subordinates and peers, I think, is simply related to the fact that some people are "all business" while at work", and not interested in your personal life until the annual Christmas party; and then they're still probably not all that interested.

If you can produce, and can show that you produce, then what you do on your own time probably doesn't matter to anyone who matters.

The problem, I think, is when there is a perception that people who work longer and harder, provide more value to a project. This perception can be hard to shake. This is mostly because for your average scientist, engineer, programmer or what have you - the contributions of one individual versus another are not at all easily established -- which invites human speculation, which invites irrational judgment.