In his Apostolic Letter entitled Marialis Cultus, Pope Paul VI states "the Church's devotedness to the Virgin Mary is an intrinsic element of the Christian Religion." His Holiness even states that we "cannot be Christians without being Marian." Father Stefano Manelli of the Franiciscans of the Immaculate focuses on this passage from Marialis Cultus as a true summary of Catholic teaching regarding Marian devotion.
If a Christian refuses to see God's glorious election in choosing the Blessed Virgin Mary as the perfect Mother of His Divine Son, then that soul does yet see the beautiful plan of human salvation. The incarnation, death, and resurrection of Christ for our salvation requires that God the Son have a human mother. It is integral to every single Christian doctrine revealed by God.
I write "refuses" to see the beauty of Marian devotion because it is something that God disperses in the soul through grace. If I person says, "I love Jesus, but I don't love Mary," something disingenuous has occurred.
The typology of Adam and Eve in relation to Christ and Mary is helpful here. One cannot credit Adam alone for God's curse over the human race. One cannot credit Eve alone. Certainly, Adam was chief and our fall from grace derives chiefly from him.
So then, Adam is the Peccator and Eve is the Co-peccatrix. Eve's role is relative, but integral.
The same is true for the New Adam and the New Eve. Christ is God. Mary is not. Nevertheless, Mary's role in the Incarnation and her consenting presence at the foot of the cross does not by itself merit human salvation (a finite human person cannot merit the salvation of anyone). Nevertheless, her role in the saving action of Christ is also relative and integral. One cannot imagine the sacrifice of Christ on the cross without her since she is the loving means by which God the Son gained a human body.
If you struggle with devotion to Mary, take the helpful advice of Saint Maximilian Kolbe. He says that we only gain knowledge and understanding of Mary "on our knees." It is something that cannot be learned in a book. This is yet another reason to pray the Rosary daily.