Jesus is Lord, neither John the Baptist or all the previous prophets and religious leaders were. He has authourity to change tradition, because He is the Lord of the tradition. He can change laws, because without Him, no law was made.

Jesus knew who He was, and He took very good advantage of it to do things the way He wanted them to have been done in the beginning before man rebeled against his God. The practice of tradition, religion was harassing, and a routine. In this way, people always got bored with it and sinned, because they knew what the law said, they could cleanse, and do it again, and again. But with the new era of Jesus, one walks in mercy, and promises between one and his/her God, you break them, it's up to you to choose between hell and Heaven.