To be totally honest, I don't see anything against looking at some of the current art and see if it still fits. Don't get me wrong, those who put time into the making of the art need, and deserve, credit, but as with many things, sometimes this kind of thing needs to be periodically looked at and changed to allow for the evolutionary process to continue advancing the game.
The art on the Jade Shield always struck me as nothing more than a spore which tends to confuse me at times because I think I am looking at Thorn Carapace. On that, I'd expect to see something spore-like. I am all for pursuing new ideas that takes this game to higher levels and I honestly look at the new pillar/tower art as a step in a positive direction. I'd love to see the Cockatrice get a makeover as I feel like I am Billy witchdoctor summoning Super Ultra Mega Chicken everytime I play an upgraded trice!