Night shift, bedtime 4am.
Keeping a circadian rhythm is critical for your health, I know flux developers agree with this.
Unfortunately for whatever reason they refuse to acknowledge that a healthy circadian rhythm is important for people who work 2nd and 3rd shift too.
I get up around 3pm and go to sleep at 4-5am. If I keep the lights down like it's night time during my biological day (at work or not), I will be tired and exhausted.
I must also maintain a STRICT bedtime, because if I go to bed later, the sun will be coming up and that will REALLY mess me up, making my sleep poor and dragging my circadian rhythm all over the place (and me with it!).
You can set a different location to sort of work around this, but given how much thought and work is put into the design of this program, I'm a bit shocked you can't simply slide the day and night transition sliders on the 24 hour bar (which could use a time label). I even tried to drag the sections to shift when they start as it seemed natural to do so...
I don't expect much of a response, but if I do get one I'm almost positive the message will basically be "Dimming your screen at night is what we pretend is ideal. Go somewhere else. (aka, you don't exist)".
No features need to be changed or removed for customizable dimming time to finally happen. Come on F.lux! There are so many people who are going to benefit from this! I just hope you change your hardliner stance before an alternative overtakes your core features by doing that first. Everything else flux can do is amazing, there's no way an alternative will be able to match it's level of development for a while so any alternative that does a better job at the basics will overtake flux. This will be a big loss for everyone.
I'll keep checking back every few years...