As I think Marks was suggesting it's just more common sense which some people really need spelling out for them.
And seatbelts do fail, as do airbags two things designed to save your life, and you don't see such press as a Wii-mote hitting a TV gets. State of the Nation FTL
Watch the video of a wrist-strap failing, ask yourself if you'd do that kind of motion with a 30 quid device, wrist-strap or not.
Could they be stronger, yep, but then personally I think it's much more fun laughing at the stupid people. It's like watching an episode of Jackass being created via the internet
P.S That website if funny, I laughed out loud reading the caption under the most recent "breakage"