"Your ways are not my ways" - says the Lord (Is.55:8f). The ways of God and the ways of us, humans don't coincide. We, humans, may expect something new which God does not give us and so we always have a "but"¡K
In the Gospel passage the children don't think and neither do the Jews - and perhaps many of us - who live our lives with our minds closed to anything coming from above. We may accept themselves or those who, coming from outside, reflect our own image. Those sent by God may be a novelty and so are not accepted.
The message of God is almost always interpreted by us, humans, as foolishness (see 1 Cor, 1:17ff). We search our own image to please ourselves and naturally we don't find it in Jesus Christ. The Kingdom of God is Joy. His message is freedom, hope, joy; but Jesus contemporaries expected a Political Messiah, a king who would make his people live within a materialistic and oppressive peace. But the ways of God and the ways of men don't meet. We don't fabricate our God: Our God is either accepted or rejected.
What is the type of God which we make? Are we fully accepting and living God as He is?
Great are Your works my Lord, make my heart like Yours.