Well, I don't really think the day/night cycle could affect the gameplay significantly. I completed several missions during Halloween and was't killed by the street mobs one single time. On the other hand, a level 5 can go to Downtown at day and can't afford leave the main roads unless life doesn't mean anything to him. Navigating in the City doesn't really get that harder no matter how dark it is, since we still have the map and the atlas. So, if the day/night cycle doesn't affect the way we play, the only thing it can affect else is the aesthetics. As the difference between night and day was always quite noticeable (the music, the lights, the "personal exterior light" and of course a still significant decrease of brightness), it's less about differing between daytimes but more about the aesthetical aspects of the nights themselves. The darker nights mostly show that it's really nights right now and everything automatically gets darker. A great concept and also a great feeling, but the city itself suffers from that. Let's say you aren't running missions or pvping at the moment and just exploring the world (what I use to do pretty often). The brighter nights didn't take the fun from this kind of activities since they didn't really hide texture nuances, but brought new aspects and colors into the world. Both night and day were individually amazing (I have to admit, the culminations of the day, especially "Sati's" day and especially in Richland weren't that amazing) and were like two sides of the coin, if you want. Now, day is the time where you still see much and night where everything just turns dark. It even takes some of the districts' individuality, in my opinion.
And here's just my main argument: If the days change from green to purple once a week (disclaimer: I only read that at the forums), what's so wrong about that kind of variation during nights, either?
And then, there are parts of the Earth where the night doesn't turn completely dark during nights (mostly at summers) so the whole night really looks like later in the evening evening or right before sunrise.
Also, because of all the lights, big cities look quite bright even at nighttime. And since this is the Matrix with a green sky and not the real world we're talking about, what's the meaning of "realism" at all? I mean if it looks better in certain aspects (c'mon people, it didn't really look that awful, did it? 
), why not simply keep it at least partially? (just repeating the same stuff for better overview lol)
I'd really like to hear your opinion about that, Stack, so I'm looking forward to your answer.
