Making a class static shows your intention
Chapter 7: Concluding C# 2: the final features: 7.2
Last updated: 5/13/2008
When describing static classes, I mostly stayed at the mechanical level of what they do, rather than why you'd want them to work that way. I did explain that it helps to keep the type from being misused, but Joe Albahari expresses an important reason much more elegantly:
I think static classes are important for clarity because [making a class static] states intention.
Exactly. Whenever there's a simple way of giving your reader a massive clue as to how you've designed your class to be used, that's a really good thing.