iOS and OS X are still full of skeumorphisms. But why do they have to be so super ugly flat low-contrasty? Why can't we have futuristic inventive super abstract UI elements that are non-flat, with proper contrast and beautiful? Most people here conflate skeumorphism with non-flat stuff. So for you antonyms:

skeumorphism <-> devoid of metaphor

flat <-> three dimensional