If you walked into a wall, they must not have had the chaperone settings setup properly, either miscalibrated or not appearing brightly enough.

I have a 2.5m x 2.5m space, with walls an inch or so past the edge of the space on two sides. There's only been a small handful of hits, and those were mostly at the beginning. My experience, both for myself and watching my friends try things out, is that the wire is annoying, but it's not dangerous. I think part of the problem here could be that it's best to play without shoes on - it's easier to tell when you are standing on the cord, which is when you can get the most tangled up. Obviously people are not taking their shoes off for store demos.

Wireless is definitely going to be a massive improvement, but I think saying it is dangerous is a bit of a stretch.