Why did Jesus speak in parables?
Jesus spoke in parables to make the kingdom of God more easily understood by the people. Oftentimes when trying to explain something, using a story to illustrate the point is the most effective way to communicate the information.
Parables were a common method of teaching used by rabbis and prophets in the ancient world (see 2 Sam. 12:1-9). It was a teaching style well known and accepted.
Parables invite the listener into the story. Which character do we identify with and why?