This really is a great question. 

If parables appear difficult to understand, then you might be onto something. Parables, contrary to popular beliefs, are not meant to make simple points. In fact, parables function in just the opposite way. All you need to do is to examine the lack of insight even among the apostles. Parables make things complex, confuse and cause the reader to think and rethink. More importantly, it is through this act of thinking and rethinking that paradigm shift can take place, which is real change. Therefore, parables will confuse, but the outcome can be true change. 

One of the most difficult statement on parables comes from Mark 4:12, which comes from Isaiah 6:9, 10. These verses seem to say that God deliberately speaks in parables, so that people will not be able to see.

This is not the best interpretation, since Jesus’ express mission is to preach, teach and save people. A better explanation is to look at this quotation in the context of Isaiah to discern why Mark quotes it. In Isaiah 6, God judges Israel for willful blindness and hardness of heart. So, it is probably best to state God allows people who want to be blind to continue in their blindness. In other words, outsiders are those who want to be outsiders. God gives to each person what he or she wants.