Witness

"But you shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me in Jerusalem, and in all Judea and Samaria, and to the end of the earth.” Acts 1.8

Nobody needs to receive the Holy Spirit to be healed, delivered from evil or to be prosperous. These miracles are natural wonders of faith in Jesus.
But to an "eyewitness" of His resurrection, a new creature and to possess His character, only by receiving the baptism of the Holy Spirit can you achieve that. He is the One who maintains our salvation until death.

Happy life

"He will yet fill your mouth with laughing, and your lips with rejoicing." Job 8.21

This has to happen to those who receive the heavenly gift, the baptism with the Holy Spirit. Their lives must flow rivers of peace, joy and life so that it overflows to bless others as well.

NEW MAN

"Then the Spirit of the Lord will come upon you and you will prophesy with them an be turned into another man."       1 Samuel 10.6

The main reason for the baptism with the Holy Spirit is to transform the person into a new man. A man that is according to the character of God, the thoughts of God, the attitude of God and overall, that he is made in the image of God, which was one day lost by Adam and Eve. 
Any other reason for wanting to receive the baptism with the Holy Spirit is a waste of time.

Did you receive?

“Did you receive the Holy Spirit when you believed?” So they said to him, “We have not so much as heard whether there is a Holy Spirit.” Acts 19.2

For the primitive church, it was common to receive the baptism of the Holy Spirit right after their belief in the Lord Jesus. Their sincere faith gave the Holy Spirit the freedom to come upon them.

Soul vs Spirit

"And so it is written, “The first man Adam became a living being.”[a] The last Adam became a life-giving spirit." 1 Corinthians 15:45

Man comes to this world as a living being but when he's born of the Holy Spirit, he becomes life-giving spirit. When he's baptised with the Holy Spirit, He's stamped with a Divine Seal.

My Son

"Then a voice came from heaven, “You are My beloved Son, in whom I am well pleased."

Mark 1:11

The Holy Trinity was identified through the baptism of the Lord Jesus. In that moment, the Holy Spirit came in the form of a dove, and landed on His head. The same happens today with those who are born of God. They're involved by the Spirit of God and then made into Children of God.