Jon, these came out originally nicknamed "Poker Peek" cards, and were intended for use in the World Series of Poker.
When the cards were brought to the tables by the tournament organizers for the WSOP, there was a near revolution going on immediately upon the players getting their first look at the cards they were being asked to play with.
Some very high profile players refused to play with them.
Regular decks soon found their way back into the series, and the revolution was aborted.
If you play poker with any regularity, you have a very specific method of peeking your hand, and although it may not make much sense if you DON'T play real bricks and mortar poker (as opposed to online), you can't peek these cards in the extremely guarded methods most frequent players like to use.
Although they were designed specifically for poker, most every poker player absolutely hates playing with them, and many won't even consider playing if they're the cards in use.