The really bad thing is that it’s only a matter of time before the Internet Archive is sued into oblivion. People are uploading full copyrighted movies and there’s no moderation at all. It’s not just cacheing that is at risk here either.
Amongst other things, the Internet Archive is the home of the Prelinger Archives, the largest collection of educational, industrial and other ephemeral films from the silent era on. If the IA goes down, the only place to access those would be commercial outlets like YouTube.