We've had our Wii since Christmas. There are 4 of us.
Me, my wife, my 9 year old daughter and my 4 year old daughter.
Not one of use have ever let go of the Wiimote, it's never slipped, the strap has never been used in anger. Even my mum had a go on WiiSports bowling and there were no problems, and she's getting on a bit.
I look at that WiiDamage site and think to myself - what kind of idiot throws his wiimote hard enough to go through a TV/Wall/Friends face ?? My 4 year old can use it for gods' sake!
I know accidents do happen, and we always use the straps. But my god there must be some complete plebs out there.