Isn't Sincerity in Our Worship All That Counts?

Malachi wrote to the Israelites who had been restored to their land after exile in Babylon. The temple had been rebuilt, thanks to the faithful preaching of Haggai and Zechariah. Worship at the temple may have recommenced, (depending on when exactly Malachi wrote), thanks to Ezra's teaching. Jerusalem's walls may have been rebuilt, thanks to Nehemiah's effective leadership. Israel's external circumstances looked good. However, true worship had not been restored, so God inspired Malachi to write this short book.