I have similar complaints.
Last year I went up in hurricane Sandy (via FSX, of course).
In real life, all you could see was clouds (I live between Philadelphia & Trenton).
In FSX (from the ground), I saw lots of blue patches between the clouds. From a few thousand feet up I saw lots of ground
between the patchy clouds.
I then flew over Atlantic City when Sandy was at its closest. I saw lots of ground
between the patchy clouds.
This is what I was looking for.
Hurricane Sandy
I bought
REX Essential PLUS OverDrive hoping that I could make heavy cloud cover look a little more realistic in FSX.
I'm somewhat sorry that I bought REX as I had some problems with it. Once I get everything running well I'll try it again.
I have a bad feeling that I'll have to work on it far more than I wanted to, just to get a heavy overcast.