The Rosary is a great private devotion that has received praise from many Popes. It is a prayer currently enriched with an indulgence, and historically has had many indulgences attached to it.
However, all that being said and acknowledged, the Rosary is not a necessary prayer.
Liturgy is a necessary prayer - every sacrament is wrapped up in liturgy, and we cannot attain heaven without the grace of the sacraments. But the Rosary is not liturgy, nor is the Rosary a sacrament. The Rosary is not necessary to attain heaven.
Not one of the Fathers of the Church prayed the Rosary.
Very few of the Doctors of the Church prayed the Rosary.
In fact, St. Thérèse of Lisieux, Doctor of the Church who was dubbed the “greatest saint of modern times” by St. Pius X, had this to say about the Rosary:
“I feel then that the fervor of my Sisters makes up for my lack of fervor; but when alone (I am ashamed to admit it) the recitation of the rosary is more difficult for me than the wearing of an instrument of penance. I feel I have said this so poorly! I force myself in vain to meditate on the mysteries of the rosary; I don’t succeed in fixing my mind on them.
For a long time I was desolate about this lack of devotion which astonished me, for I love the Blessed Virgin so much that it should be easy for me to recite in her honor prayers which are so pleasing to her. Now I am less desolate; I think that the Queen of heaven, since she is my mother, must see my good will and she is satisfied with it. Sometimes when my mind is in such aridity that it is impossible to draw forth one single thought to unite me with God, I very slowly recite an “Our Father” and then the “Hail Mary”; then these prayers give me great delight; they nourish my soul much more than if I had recited them precipitately a hundred times.”Eastern Catholics use the Akathist Hymn, not the Rosary. They get to heaven just fine. The Church got along just fine for over a thousand years without the Rosary. The Rosary is a good personal devotion, but it is not necessary for salvation.
The Liturgy of the Hours, precisely because it is liturgy, is infinitely more valuable than the Rosary. The Liturgy of the Hours actually extends the grace of the Mass through the day. The Rosary, because it is not liturgy, does not do this. It does not matter what any private revelation, such as Fatima, Lourdes, etc., has to say on this point. Private revelations might recommend private devotions to private individuals. Private devotions are never, under any circumstances, greater than the liturgy, even if the recommendation to use that private devotion comes from a private revelation. Liturgy is always greater than private devotion. Period. The Rosary is a private devotion.
"Catholic" means "universal." Catholics can have different personal devotional practices. That's why we have different religious orders: Jesuits practice different personal devotions than Franciscans who practice different personal devotions than Carmelites. There is nothing wrong with deciding that a specific personal devotion is not for you. The Rosary is a specific personal devotion. It is quite possible to be a faithful Catholic with a deeply Marian bent and yet not pray the Rosary. Despite what many Catholics will tell you, there is nothing wrong with this.
As a Catholic, I can recommend my spiritual devotions to another Catholic. However, as a Catholic, I cannot deprecate other Catholics who decide my personal spiritual devotions are not helpful to them. My personal devotions are for me, their personal devotions are for them. Perhaps they find the Rosary helpful, perhaps they don't. Either way is fine. Either way is fully Catholic. That's between them and God. I have no business in that conversation.