Is "Mixed patterns on backs of the cards" really a good idea? For one this makes the cards unplayable for almost any game. I do not understand this.
Some decks are made for serious card play. Some decks are a bit more whimsical, meant for absolutely unserious card play. This deck fits squarely in the latter category. It lacks many of the features found in a practical deck, but that doesn't render it unplayable - just less desirable to some, especially people who use cards for a specific purpose, such as magic or cardistry.
Trust me, I didn't understand them much when I first encountered such decks, either! They have their fans and can actually be quite fun and interesting - but they're not what you'd call "all-purpose." Not a crime, but more of a handicap when it comes to sales. The creator was smart in going for small-batch print runs, so she's not left holding the bag with a lot of unsold decks.