This is a serious oversight on apple's part (Jony's?). The Cons FAR outweight the Pros on this one.
Pros:
1) Looks "pretty" and perhaps "balanced" from a design perspective. the icons in the folder match the tiny icon layout when the folder isn't open.
Cons:
1) My apps are now in new locations on the screen making my finger memory useless, having to learn all over where certain apps are requiring much time searching my screen and swiping to excess pages within a folder.
2) Prime screen space wasted! The screen is very small to begin with, and every pixel should be well utilized!! if app icons fit four wide, then MAKE THEM FOUR WIDE PLEASE!
3) So much unused space on the screen makes it look POORLY DESIGNED AND UNBALANCED from my perspective, negating the only pro listed above IMHO.
PLEASE reduce the space between app icons and make it 4 in a row as it was in iOS 6. SERIOUSLY. I couldn't care less about it "matching how it looks when the folder is unopened".
Jony Ive is terrific and has done a phenomenal job addressing a lot of the design setbacks of iOS 6, but THIS is the one and only thing that iOS 7 has FAILED at.