Actually, they aren't. Softmodding the Wii is so risk-free it's bloody hilarious.
... But don't tell anyone this. Or the fact I said it.
About the rumored Smash 4 demo at E3
If this Smash game is also going to be for the 3DS then the demo might be downloadable. Having it available as a downloadable demo for a short time might be good marketing for the 3DS version. However I can see downsides to it, and there is a huge possibility that it wont happen anyway.
They could make the demo downloadable for the Wii U as well.