In response to Inkie...
Strait from the NWT
Exodus 20:4 "You must not make for yourself a carved image or a form like anything that is in the heavens above or that is on the earth underneath or that is in the waters under the earth." 5 "You must not bow down to them nor be induced to serve them..."
I can see your point about the important part is not worshiping them. How about this though...
I have several Buddha statues in my kitchen. I have never once worshipped them. I never plan to either. However, if a JW Elder was to step into my kitchen, a Judicial Committee would soon be formed. It would have nothing to do with me, but because somebody else worships those images! Images that inspire reverance in the form of worship often come in the form of heavenly creatures, which again surprises me that Jehovah God would want two Cherubs on top of the Ark of the Covenant.
So for the sake of keeping his people clean and acceptable to him, it surprises me God would want an image on the box.