Boxes are historically the weakest component for game durability -- even considering that they get the most abuse.
Until fairly recently, game manufacturers almost invariably designed boxes primarily for their marketing suitability. And you still see the effects of this focus with the kind of family games you'll see in a discount store. Large flat boxes with garish print and flimsy construction may be OK for a game of Monopoly, Sorry or Barbie Fashion Show that's fated to end up in pieces before the week is out, but it's very frustrating for serious adult gamers who expect to get years of play out of their games. I used to hate the old Avalon Hill flat boxes. They just didn't hold up to much Geek carry at all. Invariably you ended up with split ends and if you tried stacking them more than a couple high you ended up with crushed boxes. If anything the old SPI plastic flat boxes were worse. The plastic would crack, the cardboard back would come off the tray part. Just awful.
On the other hand the Avalon Hill bookcase game format and the similar Bookshelf games from 3M were great -- especially when sleeved. I have some of those games that are more than 40 years old and still intact. While AH was in business I would sometimes order replacement boxes, although I rarely ahd to do so with bookcase boxes. On the other hand my Midway box is the third one (and it's fallen apart now).
One of the salutary effects of the German game influx has been to improve the overall quality of game boxes. Even back in the 1980s when I was stationed in Germany I was struck by how much better quality the German game components were. The boxes were much sturdier as a rule.
These days, while a few wargame makers still publish boxes that won't hold up to well, the majority seem to have realized that wargames have a long life-span and the box needs to be designed accordingly. Outstanding among the publishers is GMT with its heavy duty game boxes -- I like to call them the "armored box." These seem like they'll last many a trip to cons and game buddy houses. The squarish box design used by a lot of companies now such as Hasbro, Flying Frog, Fantasy Flight, Days of Wonder and others also seems pretty durable and stackable.