Some toys have cool packaging...I might buy extras to keep misb because of that. Usually, smaller, less expensive figures. As for things stored in boxes that I never see...again, knowing I have something in pristine condition ready to open if I ever want is nice, another great thing is forgetting what I have and then rediscovering things every time I open a box. It's better than Christmas when I can go through any random box and find gems in every one of them.
One Macross related example, I don't remember buying any 1/48 VF-1s back in the day and always longed to have one but they are so expensive now. One day, going through old receipts, I found one for a 1/48 V-1J Max with Super Parts, a grail to me. So now I know I own one and that is fantastic.