Vic - We don't think it was intentional, just a side-effect. Awhile back they added additional more "secure" modes of connecting to the AppleTVs, but left the "None" security option. With tvOS 10.2, they removed the "None" option and finally required everybody to do an additional security handshake.

Why though, I have no idea. The security handshake anybody can implement (no secret keys are required), so what's the gain? Furthermore, how much security does your audio speaker really need? Password protection seemed good enough to me.

So the mystery remains.