I think one thing which is affecting which songs seem to have disappeared is the fact that songs we learnt at school eg drunken sailor are now no longer part of 'singing' and have been replaced by Disney and the current 'pop' favourites.

Whereas I am all for keeping up with the times it seems a shame to totally ignore this early introduction to a DIFFERENT type of music for most children. At least then they have heard it even if they reject it!