Liturgical churches use a liturgy or order of service, a balance between Ordinaries and Propers, both packed with Scripture. The Ordinaries provide unchanging structure while the Propers provide variety. It parallels God's creation - every day is 24 hrs, but each day is different. Humans have a need for structure and routine - we get quite irritated when those are removed or changed randomly.
Some suggest structure might hinder the Holy Spirit. But even churches that don't consider themselves liturgical have a start/end time and some order of doing things, why isn't that confining the Holy Spirit to work on our schedule? Second, God as Creator of an immensely complex world, seems to have no problem working within the confines He has created. Can we even limit Him?
Days make up seasons, which make up years. So, too, the assigned readings of the lectionary take the Church through seasons and years. This has many advantages:
Elements of the liturgy can be traced back to New Testament (Acts 2:42) and even to Old Testament times. Leviticus concerns itself with how unholy people can approach a holy God, and parts of the Liturgy do so as well (only through Christ's blood!). At a time when people are struggling with loss of identity, connecting with believers from thousands of years ago is beneficial.
Isn't the liturgy full of meaningless/uninspired repetition?
It is true you can say the words mindlessly, but you can also really mean them. The same is true when you tell your spouse "I love you" for the thousandth time--hopefully you mean it. Consider the "eternal liturgy" sung in heaven in Revelation 4:8. It is never ending and very repetitious, but it is true and apparently pleases God who created the four living creatures.