Why the Lord Taught in Parables
One use of parables is to protect people from profaning good and truth. Because they do not know the spiritual things the Lord is teaching, they cannot profane them.
What is profanation?
AC 8148:4e. Profanation is the acknowledgment of truth and good and yet a life contrary to them.
AC 1327:3. No one can profane what is holy except one who is in possession of the knowledges of faith, and who acknowledges the truth of them.... The case in this respect is the same as it is with a man who does what is evil, but does not have in mind what is evil. To him the evil that he does cannot be imputed, just as it cannot be imputed to one who does not do it of deliberate intention, or to one who is destitute of reason. Thus a man who does not believe that there is a life after death, and yet performs external worship, cannot profane the things that belong to eternal life, because he does not believe that there is any such life; but the case is quite different with those who know and who acknowledge these things.