The language wouldn't have lost much without tuples actually. But they do at least have direct pattern destructuring utility. Anonymous enums don't.

They also don't pose potential future awkwardness if/when variant types become a thing.

While I agree with you that anonymous sum types are useful, the language designers tend to avoid anything that might include a hidden cost (in this case either the size of the enum or cost of boxing). Something along those lines might end up in the language eventually, though.