Banning a card is probably the point where you're wondering what happened. While it might only be a tournament level ban (let the card be played casually), it not only effectively turns one card into a dead card for tournament players but also still leaves it alive to forever plague the casual playing field. Basically this will not only annoy the people who have the card but also annoy the casual players who now still HAVE to get a tournament useless card to play in casual if they want to stand a chance.
Nerfing the card is definitely something that will get some people in maddened fits of rage but it's a solution that allows the card to still be useful to both casual and tournament players (unlike banning the card).
The buffing of every not-so-great card to bring up the power of every card to a kinda-great level only makes the problem worse in my opinion. It not only limits the scope in which new cards can be made but it also makes the cards that were originally overpowered, weaker. Which will result in just as much whining from those owners as a nerf. (Because after all every cards power is going to be compared relative to another card, a half bad card is great compared to a fully bad card, and so if everything gets better its _effectively_ the same as the strong cards getting weaker, only it closes the scope of new cards since new every new card has to be at the similar higher power level.)
Well thats the end of my rant ;D, but yeah, I'm one that would vote for nerfs to balance the hideously overpowered cards. (Or as dawn said, bring out new sets with other potent abilities, but you've really got to be extra careful with the balance, as theres nothing worse than feeding even more overpowered cards into the hoards)
Protect our forests!
Don't kick, punch, bite or hurt the trees!