I'm currently working on weather system for new PBR lighting and I'm focusing on realism + performance. I have an idea but some people might not like it.
If you saw any video about "realistic graphics in games" on youtube, probably it had overcast weather with maybe rain. Why? Because sunlight is expensive to calculate with bounce calculations, even you let it use a lot of resource its never going to look good compared to overcast weather. Because games lack of very small details compared to real world and sunlight is shaper than overcast lighting.
I'm playing ETS2/ATS2 to drive and relax, probably most of players are playing ETS2/ATS for same reason. Thats why I don't like sunlight even if it was looking good, because its sharp and bright, adds a lot of contrast to scene which makes it less relaxing.
I want to make the weather always overcast with a lot of different types of skies and clouds so it would feel different most of time even its only overcast weather. Also I want to disable night because you can't see anything and lights are expensive to render.
PBR lighting already improves realism a lot but I will also try to make a better rain system and reflections to add more realism.
And lets not forget, no sunlight = no shadows = better performance. Even you have good gpu, you can't have all the shadows for the scene which makes the experience less realistic.
Even with default foliage it makes huge difference in terms of realism:
Pros of overcast only weather:
Better realism
Higher FPS/performance
Different types of overcast weather with small details
More relaxing experience with softer lighting
Probably better rain system and reflections
Cons:
No night experience
No sunlight to feel high contrast lighting and time of day