I always liked the idea, to review (or have essays about) books that aren't brand new.
Why should potential readers only get the chance to be pointed at the latest stuff, when out there, there is so much timeless, immortal stuff? (I once tried to establish a monthly review-section of not-new books in our local city magazine, but failed.)
I never understood, why only new books should be reviewed. Or why radio stations should only play the actual top-ten instead of immortal music of a previous decade.