I wonder how these points relate to the high satisfaction rate of iPhone users. Or maybe there's no relation at all?

Probably not much. Most of the skeuomorphism is actually relatively new.

Point is, actually, that it will be no more difficult to use than a UI with plain graphics, so if the (ugly) leather makes people feel better about it, why not?

No, I still don't like it, but the thesis in the article makes sense.