I would vote if I could for more realistic clouds that don’t look like volcanic ash. Also I would like to add that if you compare the white of an airplane paint with an illuminated face of a cloud, it is clearly visible that clouds are very grey, were they should be as white as possible on that part. Also cloud density is another thing that needs improvement or even an overhaul. I completely agree on all points made here in this thread and I think that cloud visual improvements should be of a very high priority tied with the broken weather system .
Cloud formations is another very important topic in my opinion as well. Right now clouds are looking awful sometimes with unrealistic and meaningless formations, where instead cloud types and formations should be based on meteorological descriptions and bibliography (as much as possible, because at the end of the day, it is just a virtual sim).
*** A very interesting presentation on cloud tech in the case of another videogame,( Horizon Zero Dawn ) contains some examples with their approach on volumetric clouds. And this was not a flight simulator, but a post apocalyptic open world videogame where almost 100% of the time, gameplay takes place on ground level. Red Dead Redemption 2 has some incredibly realistic looking volumetric clouds as well, even better than MSFS 2020 in some cases.