In my extremely unscientific personal test, the iPod data cable actually came out of my iPhone with less force required than attempting to unplug the MagSafe cable from my laptop.

Of course, that wouldn't be the case when the pulling isn't completely in-line with the socket (although you can exert quite an amount of strain on a MagSafe cable by pulling it out sideways). I think it's too simple to assume that MagSafe wouldn't suffer from this problem.

The explanation given by the parent post rings true for me, certainly I've had these kinds of splits in plenty of cables with traditional "strain-relief" on. I think I'm going to stop unplugging things by tugging the cable. :)