Why did the people in Shakespeare's time talk different from the way people talk today?

Well first it was a different time, time passes and things change. We don't talk like them because we are a modern generation, things changed.

Shakespeare was alive during the Elizabethan era/age. During this time, England was very posh and proper. It was important to be polite and sophisticated. I'm not sure how to relate that to the way they talk.