Would this be hard to code or create alot more traffic on the servers somehow? I'm no expert but I could imagine the development team not having enough time/resources to implement this. (edit: just saw Pika said the exact same!)
To record the number of time a card is played, the development Team (which is not big) could either use the already existing statistics (
http://elementscommunity.org/forum/index.php/topic,20533.0.html) which are sadly not focussed on the arena. They could also create a new database centred on the arena by simply using the deck-codes one submit to the arena.
Concerning the attribution of the different handicap values, I have no idea how hard it is to code. I however believe it would be similar to what is already used to attribute the rating value and electrum rewards in the various leagues. Concerning the server resources, I suppose that such things would be only a tinny bit of the access required to submit a deck but I might be wrong.
The only way to have a clear answer here is to ask Zanzarino or another coding professional.
Also, I don't think that what the thread opener suggest with actually affect anything. if mostly because the people that put these decks doesn't even care on how many electrum will gain or the "score" penalty of the deck if what they check is number of win-loss. (and face it rogue decks featuring awesome cards as that earth armor will probably loose more than win)
Be carefull, the rating of a deck is different from your personal score. Your personal score affect the level (0 < level < 80 - 69 on the picture below) and the league (bronze, silver, gold or platinum - platinum on the picture below) of the AI decks you submit. The individual rating (97 on the picture below) of an AI deck affects the rank of said deck in the leaderboard (100 in the picture below) and indirectly the chance you have to play against it. The handicap system would not affect your score but only the rating of the deck. It means that with a higher handicap a deck would probably have a lower rating and therefore a lower chance to be played against or a higher chance to be kicked out ... No need that the players decide to change their deck for the effect of the system to be visible (You don't need to sell your stock options from them to worth less) ... Their deck will win as much as before but they'll have a lower rating ...
Also about human nature, people prefer to go with "what wins" rather than consume energy thinking a deck that is uncertain it will be any good. (if not look at how creative are people outhere on other card games)
I don't know why so many people go to casinos then. Some people are players. If playing a heavy armor/otyough deck (which btw can be scary), you can win 10 times more electrum than playing a firestall you might still give a try (specially if you win only 4 times less).