Think about this.
Decks already cost $1.97 - $4.00 depending on where you buy.
Even if you buy in bulk, the cheapest you can get decks for is about a dollar a piece.
Now let's imagine they start making the boxes out of plastic....
Did you see the price jumping up ridiculously high as well? Good.
If the card box is really a problem for you, go out and buy those plastic baseball card holders that can carry 75 cards...or roughly 60 bicycle cards.
Walmart carries the above plastic cases right next to the baseball card section, near the magazines.
I think the card box is fine how it is. I have no problem keeping mine in good condition.