A few of my comments.
Firstly, the Spiritual Exercises by St Ignatius Loyola are not a treatise on the spiritual life nor were they meant to be. St Ignatius himself experienced some very powerful mystical graces and illuminations from God which mystical graces generally affect the soul permanently in one way but are transient in another way. Most people don’t experience these kinds of graces which are pure gifts from God and St Ignatius received these graces for specific purposes and to help ordinary Christians to be better Christians in doing God’s will such as discerning a vocation in life or fulfilling God’s will more perfectly on a daily basis in a vocation they are already in.
Secondly, Jesus Christ is the Way, the Truth, and the Life. We are Christians because we follow Christ, his teaching, the way he lived on earth. Jesus is our example and Way to heaven and eternal life with God. So we study his life as we know it from the gospels, the writings of the Apostles who knew him so as to conform ourselves to the incarnate Jesus who is a God-Man and be united to him in truth and love. We may also study and imitate the lives of the saints who were conformed to Jesus. But, there are many paths to God just as there are many saints with various charisms. To imitate Jesus’ life on earth and to meditate on it so to conform our lives to his is going to naturally involve the use of the imagination and picturing to ourselves various gospel scenes. Jesus is not a pure spirit as neither are we but he has a human body like we do.
Thirdly, various desert fathers of early Christianity, monks, and the early church fathers whom we call saints are not the only Christians throughout the history of the Church that were saints. We have saints in every age of Christianity and with a variety of charisms. The early saints are not necessarily greater or more holy saints than those that came after them. Later saints had the advantage of building as it were on the teaching of earlier saints and making corrections if necessary. Divine revelation and various doctrines of the Church have become better known and understood through time through the enlightenment of the Holy Spirit.
Fourthly, Christian mysticism has a long tradition in the Church and there are representatives of it throughout the Church’s history in various ways and among many saints. Some difficulties involved with the mystical experiences of the mystics and contemplative prayer in the Church’s tradition was trying to put in human language that which is beyond human language as well as relating their experiences to Church doctrine and sound philosophy. Two great masters and doctors of the Catholic Church in more recent times of the spiritual life and the mystical life or infused contemplation are St Teresa of Avila and St John of the Cross (16th century).