you are not the first to suggest this and i think everyone (except a few crazies that make the exception) would like/use/appreciate this. best of it, the foundation is already there, in form of the CW interface. in a day you could change it to save different forms.
if i remember right the biggest concerns came from people who where worried about gear and rune changes. personally i would use the item#'s and the problem is solved, but even if you dont do that then the CW interface already provides the solution to this and simply doesnt update gear, forms, runes until you actually update it.