I have been looking for such an option, thinking there was. However I was unable to find it. However - I just found it to be under the "disable" menu instead of general preferences. Thank you so much.
Yes we should expose that as a separate parameter.
We designed this to handle lighting your "whole house" and not just the lamp near a screen, so if you have a bunch of people living together, they usually don't want to have the lights change because one person disables f.lux :)