Question then - why do so many Catholic churches have statues and altars dedicated to Mary?
We venerate and honor Mary. To her is owed hyperdulia. To the Triune God alone is owed Latria.
Catholics and Orthodox do not understand worship the same way Protestants do. To us worship as defined in Latria involves that adoration due God alone and it is also sacrificial. Thus its central place is during Divine Liturgy when we receive the Eucharist.
We have those statues to remind us of the love, fidelity and hope of the Virgin Mary. In her we see the promises that God has made to all faithful fullfilled. By her obedience to His Word both written and living she shows us how a will illuminated by Grace unites with the Will of God to live out perfect faith.
For this faith she has been taken up body and soul to be with Father, Son and Holy Ghost and to live in all happiness for eternity in heaven with them.
The statues and icons are much like having a photograph of a loved one which we look upon to make us feel closer to them.
For one thing, because we imitate the Lord Himself, who honored his mother, the Virgin Mary, in accord with the 10 Commandments.
For another thing, because we revere the Gospel and the greeting the Gospel tells us the Lord’s own holy Archangel Gabriel used when he addressed Mary (”Hail, Mary, full of grace, the Lord is with you! Blessed are you among all women, and blessed is the fruit of your womb, Jesus!”) and we think of her and treat her with the same great respect that Gabriel did.
Another reason is that the Gospel reveals to use that Mary is meek and humble and yet ALL GENERATIONS SHALL call her blessed because she believed and trusted the Lord and because her soul glorifies the Lord, and because she was given such an august role in Salvation history as to be the bearer of the Christ child.
And still another reason is that the Gospel tells us that from the Cross, Jesus gave His mother to us to be our mother.
Finally, because the Book of Revelation tells us that the woman who appears in the heavens and gives birth to the one who defeats the devil dragon wears is exalted and wears a crown of stars.
‘Nuf said.