I don't do it because I'm lazy. All the toys are in one basket and now that she knows how to open that basket, she gets to pick whatever she wants, whenever she wants it.
But I have experienced with toys and chews alike, that if it disappears for a while and then reappears... yeah, it is like the most amazing thing on the planet to her. So I definitely think rotating toys helps keep them "new", I just don't like doing it