Are file permissions in files on external devices silly?

[tchomby]

A friend of mine connected a USB external hard drive up to his ubuntu laptop. 
It had previously been used on a mac, and had some files on it. He can't access 
the files because the owner is the username used on the mac, different to the 
username on the ubuntu laptop, and the file permissions are set to let just 
the owner read them. At this point my non-expert friend was stuck and had to 
ask for help, having no idea why he couldn't access the files, and blaming 
ubuntu for it. He said "they have a little x next to them."

Now I know this problem is due to file permissions and may happen on mac or 
windows as well. But isn't this silly? He's in no way prevented from accessing 
the files. He can access them, or change their permissions, as root. He could 
even create a new user with the username used on the mac and access them that 
way. So I think the security value of this is nil and it serves only to annoy, 
because he has to fiddle with the file permissions as root before he can access 
them, and has to ask for help to do this.

So I'm just wondering if something can or should be done to avoid this 
situation, and prevent the user from having to workaround it manually. I 
hesitate to suggest it, but if the user can't access some files, but is a sudo 
user, then really they can access them in a few clicks of they know what file 
permissions are, could we do something to the "You do not have permission to 
access those files" error message, like add a button to it that says "Change 
file permissions" and when clicked recursively changes the file permissions 
appropriately (asking for the sudo password first).