¿Cual es la forma correcta? Why don't you want? Why do you not want?
Both are correct. What was originally just a contraction of "do not" has become a word in itself, and can now be placed where the two separate words can't.
Both "Don't you..." and "Do you not..." are correct, but you can't re-expand "Don't you..." into "Do not you...".
The meaning of the two are the same, but "Do you not..." is considered more formal in some situations.