I think because software UIs have essentially binary actions. You either click, or you don't. You are hovering or not. You save, or you don't. Even a trumpet w

I think because software UIs have essentially binary actions. You either click, or you don't. You are hovering or not. You save, or you don't. Even a trumpet with only three keys, has all sorts of shades of gray depending on far you press they key down, and your air pressure, how still you hold the instrument, etc. I can imagine an UI that uses proximity to guide you with UI hints, but it wouldn't change the binary nature of the action being taken. Some of this info is considered in analytics, like rage clicks, mad mouse movements, etc, but that doesn't change the result of the software.