The reason I believe every deck has its own personality is partly the same as why I view the tarot works in general. All of the images in the deck cause a reaction in us, and some of them are different person by person, and some of them are universal symbols that cause a reaction in all of us: white-pure; flowers-growth; sun-energy.....etc.
These same images done in different ways can evoke feelings and images in us that differ depending on the way they're depicted. Our subconscious reacts to these images and changes the way we look at the deck or ask the deck questions. That's why I feel every deck has a personality, because each deck is so individual.
Yes, cards are just cards, but if the artwork is unique and affects you, you will develop a relationship with it. It will start to speak to you. I tend to think this is just our subconscious imagination helping us out, but it certainly works.
For instance: I recently purchased the Deviant Moon Tarot. For me personally, it's a very fun, but sarcastic deck. Sometimes it will slap me on the face for not realizing something and then laugh at me about it, all in good jest. Is the tarot actually doing this? No. But it's the reaction my subconscious has when I see these particular images represented by a particular artist's personality.
Yes it all comes from us, but our reaction to different artwork can produce different feelings, thoughts. Just as if you were to watch two different movies based on the same book but starring different actors, a different screenwriter, and a different director. Each movie would definitely have a personality all its own!
Sorry if that was rambling, but it's a very abstract concept to explain.
