(disclaimer: this post is me “thinking out loud, so I apologize for any lack of clarity)
Yes, relevance is a worthy goal, but it should not be our only goal.
What about learning for learning sake? Scientists learn out of curiosity, not utility. My favorite learning topic is not of much use to me (philosophy of technology).
Understanding footprints in rock is not relevant to students, but every student had ideas & wanted to share their thinking as we tried to figure out some footprint fossils. We (teachers) are not future predictors. There us some value in exposing students to diverse information. I hope my students develop flexibility in their thinking & a love for all learning, not just “relevant” learning. We send a dangerous message if we imply to students that only relevant learning is valuable.