Jesus Christ should not have gotten any reason to be baptized. He has not committed any sins. He was sinless. So, why did he needed to be baptized? The reason he accepted to be baptized by John the Baptist is seen in His response to John. When John asked Him, are you coming to me to be baptized seeing I am the one who has the need to be baptized by you. Jesus answered him: so it is our duty to fulfill all righteousness. Sometimes, it might not be according to what is expected but we just have to accept it or do it because responsibility is upon us to fulfill all righteousness.
We can say that Jesus Christ being baptized was to fulfill what was written concerning Him. He came into the world to do the will of His Father. He did not come to do His own will. It was the purpose of God that he came to do. So, His baptism was one of the ways of fulfilling the purpose of God.
Also, though Jesus Christ was sinless yet he submitted himself to be baptized. He did that to leave us an example. That has made baptism a necessity for every follower of Christ. If Jesus Christ himself was baptized, why should you not be baptized? It is a call to everyone who is a disciple of Jesus Christ to be baptized.