Wasn't that the problem? I've never owned a Mac so I don't know, but I thought they changed it because the other plug was too secure, and people tended to pull their laptops off of tables when they tripped on the cord. I'd rather have to plug the charger in more often than have a broken laptop any day.
I thought they changed the plug because the old plug was too thick for the design of the Retina MPBs. If you have an old power adapter can compare it to the thickness of the Retina MBP you can see they'd have had to make the Retina MBP thicker or else have it not taper where the power supply meets the body.
That's the same thing I thought, until I got my Air (2012 model with the new charger).
Within my first half hour I had accidentally unplugged it 5 or 6 times, just by moving it around in my lap. Pick up the cord and plug it back in each time, it starts to get a little annoying.
I've gotten better with it now, but I will still do what this video shows, where it doesn't completely unplug. You don't always notice until you get a low battery warning when you thought it was plugged in the whole time :(
