This bugs the shit out of me, why the fuck do these games have run buttons despite having analog controls. Mario Galaxy/Sunshine/64 felt so good. This feels like a step backwards.
I would guess it's because half of the control configurations don't use analog. I agree though, it's weird that when using analog controls that maximum usage wouldn't just cause running. Honestly, it's so natural to me to be hitting the run button that I didn't even notice it until you mentioned it =P