I think it is a shame we don't have some kind of structure in society that a person can take a type of sabbatical at 30, 35 or 40 to read these books.
Even respecting St. John's to the degree I do, I don't know if that is the path I would want my 18 year old kid to take. It seems to me that a person needs a decent amount of life experience to contextualize the importance of what is contained in the classics.
Otherwise, it seems like it would mostly be memorization for test taking purposes that is quickly put to the back of the mind.