As far as I am concerned the box adds zero value.
Most would disagree with you, like you said thought to each their own. I used to sell antique toys and it would blow your mind how much more money a box or original plastic blister would make the toy bring. This is just not true for guns or antique toys, but lots of other things as well. There was also plenty of people making fakes boxes, cards and blisters, but that is why you have to be knowledgeable in what you spend your hard earned cash on. I can spot most of them a mile away, but some would actually require me to bust out a jewelers loop and put it under a bright light to check gluing and the plastic, thats how serious it got
Eric