I get what you’re saying, and I agree. I think it is a general issue with the clouds at the moment. Even stratiform clouds suffer from this. But, they are always a really gray hue. This darkens the sky unnecessarily. Before sunset today, I loaded up at IAD (I live right next to it irl). In real life, we definitely had overcast clouds with snowfall. Looking out my window it was still somewhat bright outside. Residual light does make it through the thick overcast layers and brighten our surrounding. It went from white to blue and gradually to darkness. In the sim, however, at the same time under live weather and live time, it was pitch dark at the surface. Overcast clouds, snowfall was accurate, but the lighting was not. If I was to disable live weather and set it to clear skies, then you could see that the sun was still somewhat up, but setting. Typical sunset colors/brightness.
The issue seems to be that certain overcast types in the sim are completely blocking out any light from above. The clouds shouldn’t be dark when the sun is up, even if 100% overcast. I’ve also noticed that in sim during daytime snow conditions. In real life, an overcast stratiform layer (especially with snow) seems brighter to many eyes than clear skies, due to how white it all is. In the sim, however, it always looks dreary and gray.