FWIW, ambient light sensors were present in (high end) devices (and displays) for ages, but they never worked reasonably on desktop hardware: basically, they should let you configure at least two points of comfort in different lightning. Eg. when it's very dark, you set the brightness that is comfortable; when it's very bright around you, you set another level of screen brightness. Finally, display brightness gets set automatically by interpolating (and even extrapolating) from your chosen settings.

Advanced configuration could allow you to tune the curve continuously (or in a sufficient number of discreet steps that it seems to be continuous).

I think I noticed my Android phone at least doing a "I'll remember a relative brightness you want for this much light outside", though I haven't checked if it's really that.