Extroversion and introversion are both equally "good." The doctrine in Personality Type, as I understand it -- and I agree with it -- is that an extrovert is the outgoing, gregarious personality, who (and this is important) is refreshed by contact with people.
This point is crucial -- when an extrovert wants to "recharge her batteries," she does this by getting around a lot of people. Extroverts spend most of their energy in the outer world. Also, extroverts tend to be good at a very wide range of things, and have a wide number and range of friends and acquaintances. The gift of extroverts is breadth as opposed to depth. A good job for extroverts is that of reporter. I heard Katie Couric say of herself, once, that she is "a mile wide and an inch deep."
An introvert's gift is depth, or intensity of interests as opposed to breadth. I am an introvert, myself. Introverts are more intensely focused on a narrower range of activities -- but, as I say, we laser in on them with far greater focus and intensity than do extroverts with their interests.
We introverts tend to spend most of our energy on the internal world of our thoughts. We have a narrower range and lesser number of friends and acquaintances. Introverts, when we need to "recharge our batteries," do so by spending time alone -- this is what we need; as I said extroverts are the opposite, they need to get around people to energize themselves.
Of course there are times when I am extroverted; and there are times when the extrovert is introverted. All of us are actually a mix of introversion and extroversion. Both have their vital strengths and unavoidable weaknesses.
Anyway, extroversion and introversion are natural emanations of the human personality.
Take it easy.