Hi, Nigel -
I think that's the point - to alter the meaning and change it from being a racist song to something more inclusive. Using the term "niggers" just doesn't fly these days, and "darkies" is barely more acceptable; so we have to do something to salvage songs that are otherwise worthwhile. I think it's better to change the song and remove racism completely, rather than to simply substitute a euphemism for a racist term.
-Joe-