It's not the end of the world...I would start using GI and that will already improve it.
Furthermore you can tweak the clouds as well to let them have more variation in shading.
For instance, increase density from 0.006 (default) to 0.015 (for example) and increase edge sharpness to 15 or something.
As you can see the clouds will have a lot more detail and features, also in lighting.
To make sure that GI works for all 6 sides search for GI and cubemap/skybox on the forums and you'll find a lot of info.
Others and I have explained that about half a dozen times before so it's out there, definitely
No need to give up on this