So... A screaming orc in armor and a woman? Maybe there'll be some feature to let us choose a race in character delection. I'd love to play as a lizardman or elf (especially given how conspicuously absent they are from DOS).
I really don't expect a day/night cycle for original sin - ever. It's a ridiculous amount of work with little return for it at this point. I would like to see one in Larian's future adventures when they can design for it from the start, but retrofitting D:OS for one now is one of the least likely things I can imagine them doing.
A day/night cycle would actually entail very little work and could be done fairly quickly. I think you're confusing day/night cycles with NPC schedules, which are two very different things.
Day/night cycles would simply make the world more dynamic--both visually and in terms of ambient SFX.