I tried one back when the UK still had them.
They are fun - so fun I went up and down a few times. (It was late, and the building was almost empty.)
They feel reliable. You hop on, you go up/down, you hop off.
You don't wait to see if the button you pushed actually did something, you don't try to find a place in a small herd of anxious people with decreased personal space, none of whom are talking, you don't get claustrophobia or any other phobia, and the jump on/off experience adds a frisson of excitement to your day.
And it's hard to get trapped in one. (Not impossible. But certainly hard.)
I suppose contact/proximity sensors at the limb/head-chopping edges would add to the cost, but conventional elevators are hardly 100% safe, so I don't really see the rationale for killing them off.