We have to understand the purpose of the book of Matthew. Matthew is written to the Jews and presents Christ as their Messiah. The Jews were looking for their Messiah to come. But they didn't want Christ. They wanted a king who could get them out of Roman rule. They wanted Christ to ride a warhorse, not a donkey.
It does not mean the Kingdom is not going to come, but it is delayed for a while. God is not finished with the Jews. They ARE His people. In the meantime we can take all sorts of application from it. The Lord's prayer is to teach the disciples HOW to pray, not hocus pocus. It's not a formula.