IMHO the most important skeuomorphic thing in UI is to make buttons actually look like buttons, i.e. they are obviously meant to be pressed. Far too much time has been wasted on trying to learn UIs where buttons are virtually indistinguishable from static text. Borderless buttons are particularly frustrating, especially when there's multiple of them next to each other.
THIS. Material Design guidelines tried to drill these into deisgners' head. But man, their damn artsy skulls are thiiiiick...
There should be a "Shadow + Fill if it's tappable/clickable. F please!" rule though in every design school. Every time I see it not followed I get a fit of rage, that unfortunately I need to swallow and not fire the designer because I know he's otherwise good at UX too.
It's should something like a "don't f drive when you're drunk rule" rule... common sense to every-f-body!
It’s amazing how many Accessibility settings I have to turn on in iOS (which restore shaped buttons, etc.) in order to make the system sensible. While I’m glad the options even exist, I am a fan of sensible defaults and Apple and Google do not have those.
