When you keep doing what you are passionate about for long enough, over time your taste and attitude about those things becomes more refined.

Your experience of a specific area of interest matures to confidently make you feel like an expert in that domain.

You become better at recognizing mediocrity, and are no longer satisfied by it.

This is important when it comes to the design of things.  Whether it is a car, a T.V., a mobile phone, a web site, or even a dance club.

You now know what you like.  How it should look, work, sound, and most importantly, how it should make you feel.

And if it doesn't do these things.  Then maybe it's time for you to improve upon it and design it better.

That is called progress.