I disagree. The current system really isn't fine right now. There two are rare card with banish only one of which sees play as far as I can tell (Alastor, Flame of Heaven). On the other hand there are 13 rare durable cards, about 6 or 7 of which see a fair to good amount of play, about 3 of which can really dominate the game (Bank, Magic Academy, and to a lesser extent, Manufactory). Yes it does suck when a common card can take out a rare one, but if banish is implemented right this wont happen very often at all. And what sucks even more is losing to a card that you only have a 0.4% chance of ever getting after any one card. What's worse is that even if you do get that card, chances aren't bad that it's only a 50% chance or even 33% to get the particular card that you want. So to fix the power level of the durable cards, there need to be a lot more playable rares with banish, or there needs to be a weight system to give commons and uncommons some chance of taking out durable cards. Getting Bank when you have about 38 or more bricks and 16 or more recruits normally equates to a win unless your opponent can deal with it in one or two turns because it outpaces your opponents resources so much while also fending off their attacks to some degree. Magic Academy and Manufactory are similar in that some decks are able to get to the point where they can reliably play them every other turn and completely outpace their opponent's attacks or tower building.
This is why I think the situation isn't fine. I would prefer to see a game where there isn't this level of inevitability.