I don't think too many people go hard on skeumorphism itself per se. It's more that the era was associated with desirable properties that seem lacking in the flat era. The primary thing that makes me gravitate to the left screenshot is the clear separation of foreground and background elements with drop-shadows. Icons were more complex and differentiated, less abstract: what is "news" supposed to be now, "game-center" became a bunch of bubbles, "reminders" and "notes" are spiraling into each other, and "passbook/wallet" has become less distinct at each step. Color is being used less and less as well (less true for top-level app icons).

I don't know how well connected it is to the power-user axis, but I would say a characteristic power-user doesn't care that they are looking a somewhat garish and busy collection of colored icons, gradients, bezels, etc, whereas the opposite sensibility favors a minimalist UI for the aesthetics over perhaps ease of locating things. The real opposite of a power-user is not a first-time user, its a non-user. The non-user is not annoyed that they can't find things that are hidden away in secret trays you have to swipe for or such, but they appreciate the resulting saved screen-space.