The marriage prep info is to help you both stay married. It is likely what you assume about each other today will ebb and flow through your life together. That is what the preparation is designed to help you both understand. That is God's design you are married, not your own. Let's face it, the early days of dating, courting or whatever can gloss over things that become annoyances later. The Marriage prep is good or only OK depending on who is leading you through it.

One key point not mentioned in the replies is that the Catholic Church sees marriage as a divine act. A Sacrament for those that understand the Catholic Church's use of the term. That God, not the human joins two people together. Sure you fall in love blah blah. That is seen by the church as God's intervention and treats this act, marriage, with very serious regard. That is the reason for the preparation ahead of time. To help you understand that what you are about to enter is a divine expression of your love for each other and God's love and intent for you both. Your job as a married couple is to help each other to heaven. Marriage is a covenant created by God, not a contract as seen by our legal system.

Of course if a person's religious formation is vague or a person doesn't buy into all this... Then it is all formality to get a Priest's signature on the marriage license. If that is the case, why bother? Go get married where it makes sense for both people. My regrets if that sounds cynical. 

Best wished to you,

Eric