There is no reason for any new language to lack tagged union types. It disturbs me that Brian Cox rejects a simple, proven language feature that he does not even understand, even though it would take all of 2 minutes of searching/reading to understand. I'm sure he spent at least that long composing the replies in that thread, never moving past the ego-threat of "will Go ever have X?" to honestly evaluate the question.
"There is no reason for any new language to lack X" is false for all X. Languages differ in their goals, and there's no feature that all languages have to have. Even basic features like assignment can be questioned.
