Yeah, I still have a few boxes from my childhood that I save for posterity, and there is at least some merit in saving large / rare set boxes from more recent stuff (I sold 2x B-wing boxes to some guy in Hong Kong for like $13 each – then again, the hassle of packing and shipping was probably not worth the $25…) But in general, once I’ve opened a set these days, I get rid of the box.