The primary purpose of healing and miracles is to be a testimony or a sign to those lost souls who would otherwise not believe in the Lord Jesus Christ.
'20 Then He began to rebuke the cities in which most of His mighty works had been done, because they did not repent:
21 “Woe to you, Chorazin! Woe to you, Bethsaida! For if the mighty works which were done in you had been done in Tyre and Sidon, they would have repented long ago in sackcloth and ashes.
22 But I say to you, it will be more tolerable for Tyre and Sidon in the day of judgment than for you.
23 And you, Capernaum, who are exalted to heaven, will be brought down to Hades; for if the mighty works which were done in you had been done in Sodom, it would have remained until this day.
24 But I say to you that it shall be more tolerable for the land of Sodom in the day of judgment than for you.'
Matthew 11:24 (NKJV)
Brethren, a man of God could heal 100 million people in Jesus name and if those people don't really know Jesus they can still go to hell.
'For what will it profit a man if he gains the whole world, and loses his own soul?' Mark 8:36 (NKJV)
I don't believe that God heals people simply to alleviate the pain or to bring healing to their body but to save their souls.
It's why He permits atheists and agnostics..even God-haters to be healed as a sign of His mercy and His will.
'The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.'
2 Peter 3:9
This is what Jesus says to the unbelieving who just want to seek after a sign.
'A wicked and adulterous generation seeks after a sign, and no sign shall be given to it except the sign of the prophet Jonah.” And He left them and departed.'
Matthew 16:4 (NKJV)
The sign of the Prophet Jonah was the call to repent!
Jonah was sent to Ninevah to preach repentance to the people so their city would not be destroyed for their wicked ways! (Jonah 3).
He who has ears to hear let them hear.