"Because it's cool."

"My people worked themselves into extinction converting our planet into a navigable space vessel, using similar technology tested and proven on another, nearby planet."

"Why would you do all that?"

"Because it's cool."

Mmhmm. It's also cool to make good cards rare enough to be impossible for your average player to get.

I like shiny things. You like shiny things. So what's wrong with having a lot of shiny things in a children's card game?

It's possible to have too much of a good thing.

YGO is a prime example of this. All too often, its rarest cards are, well, junk. Shiny junk, but still junk. Other times, they are so critical to decks that they reach 50 dollars + upon release.

Do I even need to explain why this sucks?

Other card games do this right. The X Rares in Battle Spirits, for instance, are well-worth their rarities without being too broken. The same goes for the LvX cards in Pokemon. In addition, the chase cards in Pokemon, while not complete junk, are mostly fun, like the 2000 Movie Promo reprints.

Something shiny and rare should be decent to play with. Not broken, but not crappy, either. Making staples super-special-shiny just to juice profits does not help the metagame - it creates an insane gap between the rich and poor players.

The Japanese sets have the right idea. The Secret Rares were usable; the Parallel Rare and Ultimate chase cards were cool. No insane rarities, pretty much rational. Save the super shiny foil for collector's items, not cards that will make or break games.

Bear this in mind when designing your own card games, K? ^_^