That reminds me of the first time I picked up an iPhone. I opened the Maps app and couldn't for the life of me figure out how to close it. 30-45 seconds of just staring at the thing. Then I saw the home button.
Yes, that happens a lot for new users. Thing is, once you DO know how to do something, it makes complete sense, and is very memorable - you won't forget it.
Sometimes the issue isn't so much making the interface usable, but instead teaching the user how to use it and in a way they won't forget.
By that logic, vt100 apps used by banks in those green terminals have fabulous UI. Users familiar with the UI are blazing fast on terminal apps. The discoverability is near zero, though.
I was referring to what takes but a second to learn and makes perfect natural sense thereafter (not to be confused with learning painful rote/ugly process). Interface should be obvious in context - but that doesn't mean the user has ever encountered that context before, and initially doesn't understand it enough to know what constitutes "obvious". If you've never encountered gravity before, walking (i.e.: stand, then fall forward, then stop yourself with a foot, repeat) is not something you'd think of doing, but is obvious once you see it done.
Sometimes the issue isn't so much making the interface usable, but instead teaching the user how to use it and in a way they won't forget.