To me it seems that the point on serialization is completely moot in languages like Haskell(what we are talking about), serialization may be hard(er) to do in a language like Java or C++ where we have a rooted type hierarchy and we can't easily add new functionality, or do type based dispatch. Haskell's type classes allow us the freedom to define new kinds of functionality on top of existing types easily. You can look at libraries like Aeson, which allows serialization and deserialization from JSON with just a few lines of code. The biggest problem is that people's view is strapped to this old dynamic Lisp vs. C kind of paradigm that doesn't exist in modern functional languages.