This is an old argument. If a language allows a switch statement where no case being executed is an option, there's an opportunity for bugs. If a language doesn't allow that, some people bitch about it being too pedantic.

A strong argument for insisting on covering all the cases (possibly with an explicit default) is that someday, someone may add a new enum value, type, or whatever, and code that fans out on that value may invisibly become invalid.