Two thoughts here:

1)  Guys who collect Lionel trains do the same thing.  The highest and most ideal form of those awesome old two-foot-long steam locomotives from the 1930s and 1940s is unopened, in a cardboard box that is entirely opaque.  These things go for thousands of dollars, and they literally X-ray them to prove that it’s in there. 

2)  First editions of books.  I buy a lot of nice books (old and new) that will have collectible value.  I always read each book at least once, for exactly the reason you mention - I would feel like I was committing some crime akin to self-love when Nicole Kidman was available to buy these wonderful books and shelve them, unopened, while I read a paperback instead.

Well, yeah, obviously the item in question has to be in the realm of collectibles in order to have value. Random sealed item from the 50’s isn’t going to inherently have value because it’s rare.

But these packs are never going to be opened (provided their children keep their grubby hands off them), so the cards that may or may not be inside are basically irrelevant. In my experience with baseball cards and trading card games, the price of sealed packs are more reliant on the supply than anything. Generally speaking, if the set is more rare, the sealed pack will be more rare and therefore more valuable.

There’s a set of Magic: The Gathering (dork alert!) called Arabian Nights whose booster packs sell for like half the price of the most valuable possible card (and you can only get one of them per pack). It’s obvious that opening packs would cost you money, overall, so it’s pretty clear that the prices of these things aren’t really tied to the potential that lies within. Some people just like unopened stuff, I guess. (Maybe the 40 year old virgin bought those packs?)

-M