Across a large enough area it's always sunny somewhere. And clouds don't interfere as much as you'd think. Add in wind, hydro, nuclear and some gas and you can handle pretty much anything just fine.
And everything you're talking about is an issue with any kind of production, I don't know why you're bringing it up as if it's unique to solar. If you're building a factory that needs high amounts of stable power then you plan accordingly. Doesn't change the fact that solar is a useful way to generate electricity. I don't think anyone is saying we have to use it exclusively. We can use different solutions for different problems.