My daughter spent a lot of time with my mother from the age of 6 months when I went back to work. Both Mum & I used to recite her the traditional nursery rhymes all the time. When she went to nursery at the age of 2 and a half she was not used to other kids and tended to gravitate to the helpers - who could amuse themselves for hours trying to find one single nursery rhyme that they knew and she didn't. As far as I know they never found one. The lasting legacy of all this is that she has a good feel for language & the rhythms of speech & songs, and picks up songs very easily. It was definitely time well spent. I think that the teaching of nursery rhymes is probably self-perpetuating to some extent, for those who were taught them by their own parents it is a chance to indulge in a bit of nostalgia and to recreate the memories of a cosy and loving time in their own childhood.