They should be included, as it simply is a valid use-case which most likely will actually be used. However, there should be many more examples or good real-world use-cases. Lack of those concerns me.
I think if you look at languages that support them natively, like F#, OCaml/Reason, or Elixir/Erlang, you'll find plenty of examples of real-world uses. Whether those would suffice to illustrate how to apply them in a JS codebase that has this proposal enabled, I cannot say.
However, having gotten used to having them, I can safely say I'll always feel hobbled to work in a language that doesn't have them, so I'm very much in favor of adding them to JS, whether or not this is the proposal that wins out over time.
However, having gotten used to having them, I can safely say I'll always feel hobbled to work in a language that doesn't have them, so I'm very much in favor of adding them to JS, whether or not this is the proposal that wins out over time.