Jesus needed to be born of man to have the authority to save mankind. He had to be of our "family." Let's hope he was born from a very human Mary; this is how he acquired his human nature. Jesus needed to be sinless to save mankind. Let's hope that Jesus was conceived by the Holy Spirit.
I'm not sure what need there ever was to exalt Mary. Our whole lives are supposed to be filled with God himself. I can only guess that it came as a result of people seeing God as harsh and distant and being afraid of him. Jesus is the mediator between God and man. If you're afraid of Jesus, then you'd look for a mediator between Jesus and man.
Jesus spoke of Mary and everyone before:
I tell you the truth: Among those born of women there has not risen anyone greater than John the Baptist; yet he who is least in the kingdom of heaven is greater than he. (Matthew 11:11, 1984 NIV)
Paul spoke of her, as well:
for all have sinned and fall short of the glory of God, (Romans 3:23, 1984 NIV)
As was said, Mary is due honor, but not because of who she was, because she didn't choose who she was, but because she loved and trusted God as a result of her choices. (You really don't see people genuinely loving God much in the NT.) She and Joseph believed what God told them and were obedient to some pretty unsettling things. Is a person honoring her too much (sometimes an accusation of worshiping her)? (Luke 4:8) Be careful not to assume a definition of worship. What behaviors does Scripture show constitute worship?
God will reward us for our good deeds. How do you think about Paul? It is likely that he earned more reward from God than Mary. Paul worked harder than all the apostles.
But by the grace of God I am what I am, and his grace to me was not without effect. No, I worked harder than all of them—yet not I, but the grace of God that was with me. (1 Corinthians 15:10, 1984 NIV)
But everyone has idolatry in their hearts in some way. Some Christians, through their actions, demonstrate they love a certain football player, basketball player, or other person more than God. I don't see why there is such vehemence about Mary. I honor Paul in my heart because of the extreme suffering he had to endure. Also James the brother of Jesus, because he turned from his unbelieving ways and became a great man of God. Moses was the most humble person on the planet, which means he suffered much. Living by faith in God is so worth honoring, that God included a list of mere humans in Hebrews 11 that had lived by faith. Anyone who lives by faith in God under trial is great in the eyes of God, and Mary and Joseph were two of them.
But none of them were divine. (What does it mean to be divine?) Mary wasn't present at the creation of the world, she was born to fallen parents, which means she had a sinful nature. Being holy is different. God set apart Mary for one of the greatest things that ever happened on earth. But for this we praise God, because every good thing about her was given to her by God.