Jesus implied that they would be healed. He abandoned his knowledge and experience as a fisherman and obeyed the Word of Jesus. When the Word of God commands us to do something we must obey and not argue on the basis of our supposed superior knowledge. 6-7 remind us that when the Lord blesses, He blesses mightily. He gives more than we ask and in a way which is far superior to the ways of man.
All men are spiritual beggars.
They are sinful. They have no righteousness of their own. They do not know what is best for them. They do not know the will of God without being told. Christians admit all of these things.