No, not at all. While we are not bound to approved revelations, the message has always been the same to humanity; repent and proclaim the good news of the Lord. We have always been told to pray, fast, and do good.
The message of Ninevah was not limited to that city in the Old Testament any more than the message of Sodom and Gomorrah was limited to THOSE cities in the Old Testament. The new fulfills the old and if we ‘slide back’ to the old ways we need reminders. The Lord Himself asks if, when He returns, He will find faith. Do you think that we in the world today, especially in the West, are living the Christian message? Do we not need to proclaim that Christ is King and show it by turning back from our evil deeds to prove we believe in Him?
Don’t fall for the secular, “Everything’s allright, Jesus loves you just the way you are, you’re good enough’ crowd.” Except in cases involving scrupulosity (which are much lower than one is led to think), most of us are pretty inclined to be like the pharisee and think God must be pretty pleased with us and how today we are living so much like Christ–oh wait, we aren’t.