I love Laurie Helgoe's, author of Introvert Power, response to this question on the Psychology Today website:
SD: What do you think is the most troubling general misconception about introverts?
LH: Wow -- it's hard to choose. I am very troubled by the tendency to define introverts by what they lack. Introversion is a preference, not a fallback plan. Introverts like being introverts. We are drawn to ideas, we are passionate observers, and for us, solitude is rich and generative. Think of all that goes on in the playground of solitude: daydreaming, reading, composing, meditating -- and just being, writing, calculating, fantasizing, thinking, praying, theorizing, imagining, drawing/painting/sculpting, inventing, researching, reflecting. You get the idea.