You're missing the difference between being unrealistic to improve gameplay, and unrealistic because someone forgot to check the historical details. Everyone knows that video game characters have an unreasonable ability to carry stuff; they do that not because they imagined that ancient people had larger pockets, but because the game would suck to play if they didn't do it. The wrong pig model doesn't affect gameplay, it's just something that nobody thought to check. If they had used the right one, it would still be the same game.