Of course the syntax sugar is a good thing if it makes it easier to write the code, but if the question is about "expressive power of the type system", it's not really relevant: Zig's type system can properly express a sum type. In addition: pattern matching is orthogonal to ADT, you can have pattern matching in both languages with and without algebraic types. Neither one implies the other.
Turing completeness has nothing to do with static type checking. Dynamically typed PLs can't express any type (except Any) yet are still Turing complete.
