Why is a 3-Fold Smart Cover better than a 4-Fold one?

Me again, with my second Smart Cover question in as many days... :)

My question is pretty much in the title. I'm generally just wondering why, from anyone who's used both, Apple is moving completely away from the original, 4-Fold Smart Covers and only making them with 3-Folds now. Are they better? Easier to use? Sturdier? My initial reaction is to think that the 4th (now missing) fold allows the Smart Cover to kind of support itself instead of putting all the weight on the magnets, but I could very well be wrong.

This is where I defer to you guys - what have been your experiences with these two designs and how do they compare?