Okay, well maybe far from polished was strong language.
I'd agree with you, it is a remarkably good-looking game. I particularly like the seemless flow of your turn, and the distinct lack of stopping and starting.
The recent addition of the 'status' bar - when you 'mouse-over' a creature is just one step in making the game even better. Instead of having to count the turns as a way of finding out when it will un-freeze etc.
I agree, that the scope of this idea is remarkable. But, I do not think it will require a complete redesigning of the core of the game. Alas, I know very little about these things. But I think it could be implemented fairly easily. I highly doubt that Elements was created in a manner that would not allow quick and easy edits/nerfs/balances/changes/updates to single cards - and in that respect, it would not be such a time-consuming task to apply a classification to a few creature cards, implement a couple new cards wh ich use this new aspect of a creature card, and then balance it accordingly.
I think that it is nice how we are getting lots and lots of new cards on a regular basis. But, if things continue at this pace, people might lose sight of the simplicity of the game. We will have very many cards that are too rooted in their function. This suggestion (Creature Classification) will rather open up and untie the rooting of these creatures. For example, a vanilla creature is just that. Medium damage, no ability, medium cost. Give a vanilla creature a classification and it immediatly opens up a whole new realm of possibilities.
Anyways, I'm glad you liked the idea and I must agree that it is a large concept. But I do not feel that it can not be implemented gradually, and systematically. Without requiring a complete re-working of the core game engine.