In the words of Einstein I think it was, "There's nothing, no matter how complicated, when seen in the proper light, doesn't become still more complicated."
I have a feeling that trying to handle day/night time correctly in call cases is a difficult if not insurmountable problem, and the opportunity for error and the payoff may not be there.
One problem I can think of right off the top of my head is whether you're going to calculate when a flight changes from day to night in flight. You have to calculate where the flight is (based on the departure and detination and TAS and then what happens if you don't go direct), when day turns to night (or visa-versa). This is made more difficult by the fuzziness as to when you can log night-time in the air. In other words, the regs say night is an hour after sunset (or after civil twilight). Does this mean if I'm at 35,000 ft, the day/night transition occurs when it's an hour after sunset *on the ground*? Because if I'm at 35,000 ft, civil twilight should be later than if I'm on the ground.