The high blue content of modern monitors makes my eyes hurt, and I prefer a lower color temperature even during the daytime. It would be awesome if night color had a day color setting as well.

Night Color is a slight modification of the Redshift widget. https://github.com/jonls/redshift
Under redshift it is possible to specify a daytime as well as night time color, by modifying the ~/.config/redshift.conf file. Cant find a way to do the same in Night Color Module.

Nothing prevents you from setting your own daytime color specifications in the system settings, Night Color only applies during the timeframe specified.