It's fortunate they were shown to be broken. Because they inherently are -- it's DRM all over again. If it wasn't publicly known they were broken, then people might put more faith in them when they shouldn't.

I'm not sure I understand your dislike of this idea.

It's signing the images, not encrypting them. This isn't attempting to deny you the ability to see the pictures. Instead, it's supposed to demonstrate that an image wasn't modified after acquisition. I think it essentially takes the pixels, calculates a signature, and then stashes it somewhere in the jpeg/raw header.

I can imagine some non-evil uses for that, like crime scene or insurance photographs. Heck, it might even be useful for online selling (here's an unretouched photo--look, no scratches!)

You're right that it's tricky to protect the signing key from a-user-who-is-also-an-adversary though.

It's not tricky, it's basically impossible. It's the holy grail for some: being able to remotely attest to the exact bits of software being run on trusted hardware.