There's an almost religious fight against "popular" books - they won't even consider thinking about reading the Lord of The Rings - let alone modern popular novels.
Picking "old books" at least means you pick for some level of quality (usually) because they've lasted that long in print.
You also don't need to get kids to read Harry Potter; they're already reading that on their own.
Who in 2025 is actually against putting Lord of the Rings in the curriculum because it is too "popular" or not old enough? It's the same age as a lot of other classic high school texts (1984, Catcher in the Rye, Lord of the Flies, etc.) And I think it's quality is actually even more appreciated now than when it became popular. It seems like it is just inertia keeping it out, plus most of the people who want to reform the curriculum want newer books than Lord of the Rings.
That is true! From what I have seen and heard from the schools around me, every year the assigned texts are getting shorter and with a lower reading level.
Picking "old books" at least means you pick for some level of quality (usually) because they've lasted that long in print.
You also don't need to get kids to read Harry Potter; they're already reading that on their own.