Same here, and I used to think people were being careless... until I started working remotely from places like coffee shops where I had to bring my charger every day. Turns out the thinner MagSafe cable will fray after a while if you unpack and pack it on a daily basis. I bet it's due to winding the cord around the brick. I use the little legs you can flip out (they've been removed on the new charger). The last few months the cable has frayed in two places. Easy fixable with electrical tape, although I wish there was a way to pack the thing without straining it.

I have never had an entire Apple charger stop working, though.