Yeah, but the Sesame Street song starts "Sunny day, keeping the clouds away" and the famous Annie song does not say "The drizzle will start tomorrow".

Yes... rain is very important but doesn't need to be all the time. Nothing grows in darkness.

Famine is bad. Rain is always viewed positively.

But gloom is definitely not portrayed as being a good thing. On the other hand light is depicted as being very good.

When the Bible refers to most things (lightness vs. dark), it's meant to be allegorical. People who take the Bible literally don't know what they're doing. If you do so, you can say pretty absurd things especially from the Old Testament. Light doesn't refer to sun, and gloom doesn't refer to clouds/rain.