Until now there is no need to make amiga secure. The main problem would be browsers but first people must start attacking Amiga computer. Else there isn`t motivation to make it more secure. Probably this won`t happen.
Multiuser is something I never needed or liked in any way. At least for a home computer system where normaly only one person is using it. If I use it I want always the full access (or as much as possible) to it. Changing between different secure layers like on unix is just annoying.