You are correct, of course iOS7/8/9 will one day look dated. But my point is if everyone hated the flat look, all three big tech companies would not be going in that direction. And what looks good to one person might not to another, its all a matter of opinion.
It's all emporer's new clothes stuff. Society in 2012 (ios6) wasn't fundamentally different than society today. It's just a change in fashion. Like how one year, short skirts are "in" and a few years later, more conservative dress will be the trend. It isn't that people are more conservative, or more risqué, it's just that the fashion, design people have to constantly change for the sake of change. If "flat" icons came before skeumorphism, we would think that ios6 looking icons were state of the art. But instead, it was reversed. Thus design change isn't done for improvement, but just to generate buzz and sales.