The use case is to get file specific icons, rather than just type specific. One thing is thumbnails, but a lot of applications and games on the Amiga for example have custom icons.
Of course that doesn't require it to be in the inode (it isn't for the Amiga - it's in <filename>.info).
On the Amiga the ".info" file can also contain additional information, such as startup instructions, as well as snapshotted location in the UI - the Amiga Workbench was close to a reasonably spatial file manager (and I really miss that..).
Security implications certainly would be different than they were at the time, in that you could trick people to start executables instead of loading the file into an application they trust, but that really is best handled by warning people on execution of "new"/downloaded files anyway.
Of course that doesn't require it to be in the inode (it isn't for the Amiga - it's in <filename>.info).
On the Amiga the ".info" file can also contain additional information, such as startup instructions, as well as snapshotted location in the UI - the Amiga Workbench was close to a reasonably spatial file manager (and I really miss that..).
Security implications certainly would be different than they were at the time, in that you could trick people to start executables instead of loading the file into an application they trust, but that really is best handled by warning people on execution of "new"/downloaded files anyway.