... it would be cool to keep the old for one version of the card ...
Yes, it would.
However, the current game client file is about 4Mb in size, if I double the amount of art, it would end up being about 7Mb.
Or... I could download the art from the server as the game needs it... but I do not personally like to see a "loading" thingy every time I click on something.
Bottom line is: the old art has to be worth the time you wait for the game to download it.
It is also impossible to please everyone when it comes down to art: well, some things are objectively ugly, but it is often impossible to classify art as simply "good' or "bad". I, for instance, hate this thing here:
But, it turns out that Picasso created it, and someone spent US$100 million to buy it and it is one of the most expensive paintings in the world. Me? If I did not know who painted it I would give you $5 to remove it from my living room.
For Elements, in general, I think that custom art is more valuable than spore screenshots.