Does it? Without strongly worded messaging, users would be apt to blindly forge ahead and run untrusted binaries, wouldn't they?

It's exceptionally frustrating to see this situation playing out. I really, fundamentally, do not trust Apple, but at the same time, this sort of pervasive code signing is an enormous boon to the majority of their users. And I think fear-mongering dialogs may be an important part of actually making that work.