I do not think that every new card has to add a new effect or ability to the game.
It would be well enough to cleverly use preexisting mechanics on new cards rather than the developer and play testers spending extra effort on new cards with new coding. Just for the sake of example, you could take an old ability like vampire and apply it to a new creature. Or even..
As a community we could use old abilities and effects to balance and tweak the current elements with less hassle!
I know this topic has been brought up before, but it seems like a reasonable plea to exercise new mechanics for a faster update with new cards. I can only assume that creating new cards with new features takes a lot more time than making new cards with existing ones. I am not saying that the game and its mechanics should never advance. I do realize that is a special aspect that highlights both this game and its community, its just that vets and new players alike should be willing to make small sacrifices here and there for the sake of speed.
I hope this makes sense, I know I did not articulate it as well as I planned. Thanks!
tl/dr: For the sake of speed some updates we should use existing mechanics to create new cards rather than spending extra time with new coding and testing.