1. Too large and heavy to carry around.
2. Requires grounding (third pin), even when devices don't need it. Other standards let devices decide.
3. Doesn't allow the cord to go straight out of the plug, it always go sideways which makes it even clunkier, harder to plug (e.g. behind a nightstand at a hotel), and more prone to cord damage from bending.
CEE 7/3 and CEE 7/5 (known as "French" and "German") are way better IMHO. I doubt they have problems with "wiggling and sparking" -- that wouldn't pass certification. And it's easy to make a plug to fit both of them, with or without grounding. CEE 7/5 can even be plugged upside down.