The Church has a lot of wisdom. We stop singing the Alma Redemptoris Mater after the Feast of the Presentation and immediately begin singing the Ave Regina Caelorum. This encourages us to begin ramping up for Lent. It is like a warm-up session before running a marathon. Even though we are in Ordinary Time, it is a different kind of Ordinary Time than that which comes after Pentecost. It is a time to say "Ready, set," before we say "Go!" on Ash Wednesday.
This was the wisdom of Septuagesima Sunday, etc. We apparently need the time to prepare for the time to prepare for Easter.