Which is also why it works, much like most threats it looks utterly mundane on the outside but once ya look closser you see its true threat. A good example is an old crate of dynamite which may look fine externally but its likely the nitroglycerin has seeped out and if you move that crate you are being annihilated.
I think it being a normal book on the outside is actually scarier. The knowledge in the book was dangerous, not the object itself.
I would never open the Book of the Dead from Evil Dead but I might open the Necronomicon if I find it at an antique bookstore or something.
Which is also why it works, much like most threats it looks utterly mundane on the outside but once ya look closser you see its true threat. A good example is an old crate of dynamite which may look fine externally but its likely the nitroglycerin has seeped out and if you move that crate you are being annihilated.