Thanks for this article about parables!
Yes, Jesus had several reasons for the parables. He wanted to teach those who wanted to truly learn from Him. He needed to hide His message from those who wanted to injure Him or His work. Then He often had a much deeper message to be recorded for us to understand today, held within the symbols and circumstances used in the story.
The parable of the pearl is unique in having at least the two meanings you describe. If we find the Gospel message, it should be to us like a pearl of great price. But Jesus Himself "so loved the world" that He gave Himself in death to offer salvation. Each individual who chooses to follow Him is like a valuable pearl to Him. He would have done all of what He did even if only one person accepted Him.
Often His stories and parables made references which can be studied out carefully and they reveal prophecy of times yet future for His work and principles of value to those who follow Him.
One example is the parable of a king who reviewed his books and found someone who owed him 10,000 talents! That's a huge value. He forgave that person, who then went out and found another servant who owed him a small debt of 100 pence. He did not forgive that person and threw him in jail. When the king found out, he revoked the earlier pardon.
There's one other place in the Bible where the amount of 10,000 talents comes up. It's the amount for which Haman gave as payment to the king, to persuade him to order all the Jews to be killed.
In the story, Esther is instrumental, with God's help, to save the Jews from this threatened death. You could then infer that the Jews "owed" God a debt of 10,000 talents.
Some generations later, relatives of those same Jews were living in Jerusalem and one of them sold Jesus to the Jewish leaders to be killed... Judas sold Christ for 30 pieces of silver, which interestingly, is the just about the same amount of silver, 100 pence, that the "other servant" in Christ's parable owed to the "forgiven" servant.
Mere coincidence? I think not. Jesus in that story revealed much about the history of the Jews as people He had led and guided, but who now turned against Him. He thus offered in this parable a bit of prophecy about His own life and presence with the Jews, especially the amount which later was paid to Judas in temple silver, to betray Him.
That's just a brief sketch of the many correlations in that particular story relating history, the nation of Israel, and Christ's parables.
In other parables, just note what items Christ spoke of which are strong Biblical symbols, and study out the connections to other stories, events, and parallels of principle! These connections reveal and verify His identity as our God, the Creator, and His qualification as our Savior too.
One other tidbit here. The word for "parable" is the same as the word for "proverb." In other words, the book of Proverbs contains similar symbolic meanings, yielding parallel understandings or prophecies pertaining to Jesus and the everlasting Gospel message that are found elsewhere in the Bible.
These are valuable keys to deeper understanding of God's Word. May God bless your studies!