Man of Honour
Funny you mention that, I bought a couple of packs recently and out of 400 or so cards, around 350 were duplicate common cards.... joke!
They should just make sets of cards available to buy instead, it's ridiculous that you can spend £500 on this game and still not have the cards you want. I see no reason why they couldn't just sell "Set of all classic cards" or "Set of all mage cards" for £69.99 or something. Surely it's lot less money than just buying random packs but maybe it will encourage people to pay rather than count on RNG.
Actually the system they have is very good. If you played Magic: The Gathering for example, you could spend double that and not have the card you want. Hearthstone lets you use dust to craft anything you want. It's very forgiving in that regard.