I mean, there is a reason they change box-art from region to region. Heck, the bigger companies probably have consumer psychologists test the outcomes of various boxes.
However, boxart becomes less and less important as things get more expensive.
Which when you think about it makes sense. People are more likely to buy gum based on how it looks then a TV.
The Boxes roll was much more important before the internet, back when all you had to rely on was stuff like Nintendo Power. However not everyone researches each game, and there are people who often go to the store just to "pick up something fun". In which case box art can play a big roll.
Another time Box art will play a big roll is likely to be a games "legs" when games drop to impulse pricing levels.
