The world changes, people change and the songs change with them. I tend to change occasional words to suit the audience in front of me. with a very few songs I have permanently changed an odd word because I don't feel comfortable singing it. This natural evolution of songs is fine by me so long as the original is retained somewhere in some form. Traditional songs are after all not just entertainment they are documents of social history and we need to take care not to dilute the content to such an extent that it no longer reflects the society which produced it.