Its a cliche of the cyberpunk genre. In the real world, the sun still rises, clouds dissipate, and people go on about their lives. Why should eternal darkness and rain be the setting for this game?
I don't think any of us are asking for eternal darkness and rain. It's just frustrating if CP2077 ends up emulating games like GTA 5 or Watch Dogs 2. We've seen it all before, and it isn't very intriguing.