I think they’re mostly trying to prevent the odd death / paralysis that still happens on rare occasion, rather than a collarbone which is usually a pretty easy recovery.

Even then, I think this is going to be a tough sell, even for pros. Or when they’re forced to wear them, they’ll complain about them a lot for the first couple seasons. But then it will actually save a life and it’ll shut them up. But will probably never be commonplace in amateur or recreational cycling.