If that's the case, then the conversation shifts from "you should use pattern matching" to "when should I use pattern matching?" Which is a pretty interesting question. Logic locality seems to be an obvious criteria (does the logic live with the type, or with the consumer of the type?).
Pattern matching is syntactic sugar for extracting values from a pattern. In a statically typed language the compiler has the option of forcing the user to handle every possible type permutation with a pattern thus ensuring safety.
Polymorphism is just a generic type.
That's as far as I know... could you elaborate more on what you mean?