You really could do away with the arrogance.

I dont think saving a few lines for a very rare corner case is a strong reason to add a language feature

Maybe they have a point? Arrogance != Wrong in Your Opinion.

Sure, though as I mentioned in other comment, pattern matching is basically a better Visitor pattern. Which is while not the most common pattern, is not that much of a niche either.

It's just an example...

And you don't seem to understand that it's about the safety of the exhaustive check not just the sugar.