May be the second time I've found a genuinely insightful piece by Gruber. Skeuomorphic design was a nod to my non-computer using father in the 90s. It no more represents useful metaphors for interfaces than steam engines represent a good way to build cars. iOS is stagnant, reviews of recent Apple designed skeuo-heavy apps bemone the lack of functionality -- while noting what must be hundreds of hours of graphics work…
"iOS is stagnant" iOS only seems stagnant because they don't have to trumpet every year about how they've finally gotten rid of ui lag or completely overhauled the system appearance. These are points in it's favor to most people.
You might not notice it, but, there is an eighth-of-a-second-ish delay between when you tap on most buttons and when the action occurs. An obvious (to me) example is when you tap on the back button on a navigation controller, and it takes a split second before anything happens..
It isn't much, but it is consistent across the OS, and it drives me crazy.