I think part of the point of the ITW ending is the mere fact that it is complicated. Life is complicated. There is no such thing as good and evil, right v. wrong. Perspective and decision making is what drives us in life. There aren't happy endings for everyone, even in fairy tales.
The more complicated you can get in musical theatre, as Sondheim has proven again and again, the more timeless, provocative and beautiful it is.
BSoBW2: I punched Sondheim in the face after I saw Wicked and said, "Why couldn't you write like that!?"