It's because iOS 7's full screen browsing didn't at nice with google's images view.
Swiping through photos in landscape would rest in the navigation bars coming back in safari, and would decrease image size by a third or more. THAT was inconvenient.
Conspiracy theorists would think apple did it on purpose, but I truly believe it wasn't. Sailing in any direction whe in landscape full screen brings the bars back, and it seems like google is working on a fix.
Then again, it doesn't mean apple's system is perfect either. Time will tell.
EDIT: just tried bong and the same problem exists with viewing images in landscape with their layout too. Try to go to another image and half the screen is gone due to nav bars. So annoying.
Apple has been working on kinks with full screen landscape safari throughout the betas. They still don't have it down.