Perhaps surprisingly, I actually find moderately low viz is less annoying at night, because you don't expect to see very far anyway, so you don't spend any energy trying to peer through the murk.
If you are primarily diving wrecks with very little marine life on them, I could see why diving them at night might not appeal -- especially if you are doing it in the open sea, with swells and current. In fact, a lot of the places like that where I have dived don't permit night diving. On the other hand, if you are diving areas with a lot of marine life, it's really fascinating to see the diurnal/nocturnal changes that occur in species and activity. Night dives in Puget Sound have become some of my favorite dives, because of the types of critters we see in the dark.
If you are primarily diving wrecks with very little marine life on them, I could see why diving them at night might not appeal -- especially if you are doing it in the open sea, with swells and current. In fact, a lot of the places like that where I have dived don't permit night diving. On the other hand, if you are diving areas with a lot of marine life, it's really fascinating to see the diurnal/nocturnal changes that occur in species and activity. Night dives in Puget Sound have become some of my favorite dives, because of the types of critters we see in the dark.