Don't you think iOS7 looks like a cartoon of the previous iOS's? It looks cheap and one dimensional. No depth.
In all honesty, I do like the older design better but the reality is 2007 called and they wanted it back. It was time to mix it up bit. When they introduced the iPhone it was important to create a connection with users through the appearance of textures, etc. as most had never had a smart phone before and were more comfortable with such a design. Something like iOS7 might have been too simplistic and techie back then.
Now, those same users are faced with Android techie stuff and newer users don't need to feel as if they using a yellow notepad or putting books on a wooden shelf anymore. Most don't even read real books!
They have no idea what the public wants.
I'd say looking at sales over the years, they do.