The "I want to do something else!" button does nothing for me. I have many "MUST" todos and only 1 "WANT" while trying this button. The button just brings me to the same single "WANT" I have.
This is actually intentional; I've noticed that I got tempted to move aside a fun project to get more 'work' stuff done. The idea of only giving you a "MUST" after finishing the current "WANT" is that you'll have to take a break from work, before you can start with it again.
Another reason for doing this is that it would be quite unfair to give you a 'work' item when you don't feel like the 'play' suggestion it's making and just want to relax with something else - it would defeat the point of the 'play' part, and would make you afraid of clicking "something else", because it might come up with a 'work' item. It's all part of the "balance between work and play" thing :)
I'll change around the sidebar text in a few minutes, to clarify on this.
EDIT: I've updated the sidebar.