Matthew is writing to the Jews. Land is important to national Israel, and all of these parables deal with family land.
Parable of the sower: the explanation of this parable is that the ground being sown is the world. This would offend those who see Israel as the garden and the other nations as the barren wilderness – the kingdom is not bound to Israel’s borders. Also a connection to Isaiah 55: the word will not return void – it will accomplish what God intends… but what does God intend? Isaiah is clear (and Jesus re-emphasizes) that the word is sown among the nations – not limited to Israel.
Parable of the enemy: the boundary of holiness is not national Israel – the godly and the wicked currently grow together there. So what makes Israel any different from the nations?
Parable of the mustard seed: What makes Israel different is that they were the first ones chosen for planting… but remember the original plan – Israel was not intended to hoard its treasure, but to grow/mature and serve the nations.
Parable of the leaven: Again – the boundaries of Israel were never intended to contain it. If it is truly leavened then it must grow.
Parable of the treasure: This is a big slap in the face – the Israelites never understood the true purposes of the land, and so they’re effectively selling it… and the other nations are seekers/buyers.
Parable of the pearl: Same as the land/treasure – the pearl (wisdom) is being sought by those who understand it… and Israel is all too willing to sell its birthright.
Parable of the net: Even more direct – the kingdom of heaven has no national boundaries – it’s being drawn out of the sea (Gentiles). Echoes of Galatians 3:26-29.
Parable of the landowner: what’s more important – the land or the treasure that is drawn from it?
Reaction of Jesus: The onlookers fulfill all of these parables by their rejection of the treasure/wisdom/kingdom (Jesus), and instead embrace nationality (family tree). This chapter should really be tied more closely to Matthew 12, since the family issue is what started this whole conversation.
Isaiah quotes aren’t in there to explain to us what a parable is – they’re there to show us that these pattern of rejection has always been true.
Israel has not fulfilled its purpose – but the covenant of God will still be fulfilled through the nations.