To me, this is a simple question.
If you want to stare at the box a while, watch it collect some dust, worry about it getting lost, stolen or destroyed, then, at some future point, if it manages to survive under your care, sell it for a profit, then by all means, keep them sealed and locked away in airtight, waterproof, bullet-resistant storage containers.
If you want to see just what all the fuss is about these decks that makes them so highly desirable besides simply the hype, then open them. If you want to appreciate the beauty that went into the art and design, open them. If you want to get the pleasure of the way they feel in your hands, glide along a table and along each other, the "new deck" fragrance of the finish, ink and stock, open them.
I open my decks - I don't care how rare they are. If I have a second copy (or multiple spares), I keep those for posterity, trading or as a replacement when the original gets damaged, worn out or destroyed. I've said this before elsewhere, I prefer actually taking advantage of the finer qualities like the design, art, handling, craftsmanship, etc. rather than the finer points of the science of creating packaging materials. 'Cause if you don't open them, that's all you'll get to enjoy about them. Well, that and the resale value if you should decide at some point to flip them for a profit.
I think a good comparison here might be the example of the two guys who each wants to buy a computer.
Now, the first guy, he has enough cash to be a good computer, nearly the cutting edge in fact, but he's so obsessed about getting the cutting edge that he wants to wait for the next new model that comes along. He doesn't want to buy something today that will only become obsolete within a week, or a month, or even a year. His major problem is that no matter how long he waits, there's always a new computer waiting in the wings to be released and any model already available for sale is already obsolete as new models are being developed. The cutting edge isn't a stationary thing - it's constantly being pushed forward as technology improves. So he ends up waiting. And waiting. And waiting.
Now, the second guy, he has the same amount of cash. He takes the plunge and buys a machine. It's a mighty fine computer, and he gets a lot of use out of it, both business and pleasure. Sure, it was obsolete the moment he bought it. So what? He's got a machine that's good enough, does what he needs it to do, and he's actually getting to enjoy using it instead of constantly waiting for that next, great model that will surpass all the others.
He doesn't even care when his friends with less money buy the same computer, or even a better one, many months later as the hardware becomes more and more obsolete and thus lower in price to make room for the newer ones. Why, you ask? Well, he paid more than they did, to be sure, but while they were WAITING to use their computers until they dropped in price, he was USING and ENJOYING his the entire time - it's like the extra paid was for the extra time he spent with his machine that his friends didn't get.
The analogy is an imperfect fit, but it is a fit. In my story, the first guy would sit on a deck of cards, waiting forever for its value to increase and increase, never once actually getting to enjoy it beyond the pleasure of mere possession of the object. The second guy would crack it open and enjoy it for what it is - a GAME, or more precisely, a construct made for the purposes of entertainment. He is deriving pleasure on many levels that the first guy never will from the possession of the exact same object.