According to the thread on NA, it won't affect the value. It's just something for display that won't ever be played anyway even if it wasn't sealed in a case.
I've mentioned in another thread on this that people into retro games pretty much collect for one of two reasons. Either for preservation or for display purposes. The NA guys mostly focus on display purposes, who has the nicest looking collection to show off to strangers or to stare at to stoke a personal ego at how great they are for being able to own something not everybody else does.
It's like when you hear about celebrities that buy a pet tiger because it would match the decor in their living room. You just think these guys are nuts and completely out of touch with reality.