In reguards to the comment on my last post, you may be right. There audience tends to be younger girls, probably because they started out on the disney channel. So I do agree that they don't want to shock there fans to much and damage their squeaky clean image.

To further my argument that the song is about illness I think that the line"but you don't know what you got til its gone" refers to being healthy. I think that no one really knows how healthy they are until something really goes wrong. Sort of like when my roomies complain about never feeling good but then when they really get sick they realize that they were really complaining about nothing. However this line could be about life in general. Nobody really understands something until it is taken away, like love or even money.