AFAIK on iOS 6, that globe button to switch keyboards is only there if you have multiple keyboards enabled. The button is removed and the space bar extends to fill the space when you only have one keyboard.
Can someone see if the same happens in iOS 7? Depending on the answer to that, I would recommend iOS 7 users annoyed by the small spacebar consider whether they really need multiple keyboards. Obviously there's a possibility they do, but for others who don't, sticking to just one may improve their situation 🙂