These are the cage nut tools:

But these rackstuds - very interesting. My main concerns would be vibration chewing through them over the span of weeks/months/years. Also they would interfere with cable management being that they stick out so far. For example you might not be able to use the Cisco cable management things that usually come with 2 and 3k series switches.
Plus I would imagine the cost is considerably more expensive - at about 66c each, that's $5.28 per U. For a typical rack with lets say 15 devices, thats $80 per rack.
I suppose most NZ businesses never have more than 1 rack so cost isn't too bad.