Yea you could add more nubs to make it lock better. Maybe four, though, and have just one nub activate the microswitch.
I mean another reason why the NEMA standard is still used, it because it's INSANELY cheap.
https://goo.gl/LMGF7EThe cheapest one is 68 cents. I mean 68 cents, that is REALLY REALLY cheap. 100 outlets would be just 68 bucks, which is plenty for an entire house.
The advantage of mine is that you can make it cheap. The plug can just be looped sheet metal, and the outlet, which would require some plastic rings to insulate, could be something similar.
The reason I have designed it with neutral to be larger is then you have larger contacts for power going out than you do for power going in. It's really not needed, but hey, larger drain than tap means your sink doesn't overflow.
My design would also be very very small, which is an especially good thing compared to the British Standard which is MASSIVE. The rings would not need to be large, as the circular shape gives them a lot of surface area.
The outlets though, I think the best idea for contacts would be:
a pin in the middle for the live power
A plastic ring that would go around the live ring.
A metal ring that would go around previously mentioned plastic ring to make contact with the neutral ring
A plastic ring that would go around the neutral ring in the plug
And finally a metal ring that would go inside the ground ring to make contact with the ground ring.
Don't have time rn, but later I will make another 3D model.