Arguably, iOS compensated much (and even added) in the original skeuomorphic / Forstall-era designs. (Famously, toddlers were able to operate these interfaces.) The crucial failure was not reconsidering this from the basics for flat UI. At this point, it became unavoidably a mix of what had been learned by users, but was not indicated anymore, because you don't want to break traditions, and what was actually in the UI language. As a result, instead of a clear language, there is now a diffuse aura of how things may work.

(Also, reportedly – I have no way to corroborate this –, in the Ive-era, designs were evaluated in print-outs, which is simply how not to do interaction design.)