Yeah, gestures show that you don't need the actual animation file in order to trigger an animation.
Sound files also can be triggered in a script without having the actual sound file.
So there's notreason why you'd have to have it in there from a technical stand point.
That temp attatch non-sense has a security hole. Sure it keeps the shell from being taken, but the shell can easily be replaced once you get the contents.
Having an animation UUID in a no-mod script would be more secure. I have no idea who thought that having people have access to the actual animation file itself made it more secure.
Sound files and textures can be harder to get ahold of because they can be embededed in a script. Which means you'd need that script. And there are several more ways to control your script working the way you want it to.
It's easier to have an object that only plays sounds under certain conditions. With animations you HAVE to have the animation in the object, and since they can be ripped out of no-mod objects the script replaced so that trolls and griefers can still trigger the animation in places you don't want them to.
So not only would this secure things for the animator, it'd also add more security for sim owners.