Barleywine
"Layers" is a good way to look at it. I like to say that the tarot is "infinitely flexible and adaptable," although that's probably a bit of an overstatement.
Even if a card's picture deviates significantly from the RWS, I have found that the creator has generally expressed a particular layer of meaning that very much resonates with the RWS meaning. It is just a different perspective on that meaning. In that way, I feel working with different decks has served to expand my understanding of the cards. It's not that each deck proposes a new and different meaning (although of course some do!), but that they are seeing the meaning of the card in a different way, or expressing it in a different way, which allows you as a reader to expand your own perspective as you work with that particular deck.
If you are simply going to go by the "accepted"/"traditional"/"book"/"generic" meanings - you don't need pictures, so why not just write the name of each card on a piece of paper and go from there ?
Doesn't work - we NEED the images - which tells you everything you need to know.