UI discoverability has massively declined with the advent of touch UIs though. You can't hover a UI item to see what it does, and there's a lot of non-intuitive "magic swipes" and hidden UI elements in smartphone UIs which you just have to know about.
Touch UI items tend to be larger by necessity (and to have surrounding padding as a safety factor, which increases their "effective" size even further), so you don't really need to do the hover thing. Just redesign them to be more self-explanatory as opposed to wasting that space.
"Magic swipes" could also be redesigned to be more intuitive, e.g. with some background soft-3D effects that make swipe-sensitive areas "stand out" from the neutral background.
Keyboard shortcuts were usually accelerators for easily discoverable menu items. Magic swipes don’t usually have the equivalent of a menu that can be used if you don’t know the swipe
