While it doesn't make logical sense, day at parkside and market square, night at downtown, dusk at waterfront, I kind of like the setting of the locations as they are now. It would be weird to work at the night club or do the movie night during the day.
Having said that, for just our home location, I do agree, I think a day/night cycle would be lovely!
Maybe there could be special 1 hour worth tasks that happen throughout the day that you can earn coins or maybe even simcash -- now that everything is so costly.
For morning: watch the sunrise, go for a jog. For midday: sunbathe, watch a daytime soap opera. For evening: watch the sunset, read a book in bed. For late night: stargaze, "simflix" and chill ;)
Also there could be mini tasks: breakfast, lunch, dinner (accordingly) that would give a little energy.