1. I think it's possible to have a hatred of C++ that doesn't stem from a lack of understanding of the language. I think the C++ FQA (http://yosefk.com/c++fqa/) addresses a lot of the dislike people have with C++ that has nothing to do with ignorance of the language.
2. Saying that C# doesn't add anything to Java isn't even a simplification, it's flat out wrong. That argument may have been slightly valid in the C# 1.0 days (although there were quite a few differences like auto-boxing, properties, and pointer support), but the languages have diverged significantly, and modern C# code using lambdas, LINQ, and dynamic variables is signficantly different from Java.
Similarly, CoffeeScript and Javascript are massively different languages - the fact that CoffeeScript compiles down to Javascript doesn't mean the languages are similar, any more than saying Clojure and Java are practically the same since they both compile down to the JVM.
You are partially right about C#, my experience with it dates back to the 1.0 version, but even with all these enhancements is it worth spending in the effort of learning two similar languages when you could be learning a different paradigm which will expand your mind in different dimensions and will make you a better programmer. If you are proficient in Java and want to move to .NET why not learn F# instead.
About you comparing CoffeeScript with Clojure is not fair at all. Clojure gives a whole new world on top of JVM, while CoffeeScript is just syntactic sugar for Javascript.
You're right that Clojure -> Java is an unfair comparison, but I do think there's significant differences between CoffeeScript as a language and Javascript. If you ignore the fact that the main implementation of CoffeeScript compiles down to Javascript, and look at them instead as two wholly distinct languages, I wouldn't consider them very closely related at all.
CoffeeScript has significantly different syntax from Javascript, different variable scoping rules, list comprehensions, a class system, and a whole lot of other features absent from Javascript. If you showed both languages to a programmer who wasn't aware that CoffeeScript compiled down to JavaScript, I'd guess that they wouldn't see much of a relationship between the languages at all.
2. Saying that C# doesn't add anything to Java isn't even a simplification, it's flat out wrong. That argument may have been slightly valid in the C# 1.0 days (although there were quite a few differences like auto-boxing, properties, and pointer support), but the languages have diverged significantly, and modern C# code using lambdas, LINQ, and dynamic variables is signficantly different from Java.
Similarly, CoffeeScript and Javascript are massively different languages - the fact that CoffeeScript compiles down to Javascript doesn't mean the languages are similar, any more than saying Clojure and Java are practically the same since they both compile down to the JVM.