Hearthstone's mana curve issues

Hearthstone differs from M:TG in a couple big ways that make creating "big cards" a lot harder. The biggest issue is that the mana curve in Hearthstone is smooth. In M:TG, decks generally have a stopping point where they stop gaining mana. In most cases, that's around 4-6 mana and almost never at 10.

The additional problem is that the game caps mana at 10. Occasionally decks can get more mana than that, and some things can also reduce mana costs of cards. However, the fact that you're guaranteed to get 6+ mana means that cards that are worth that much are worth appropriately less.

The value of a 6 mana card in M:TG is a ton! You might never get enough mana to play it in a real game unless your deck has mana acceleration. Most 6 mana cards are expected to basically win the game on their own. By comparison, a good 6 mana card in Hearthstone is... well, a 6/7 ogre or a 4/2 haste/divine shield. Those cards give favorable card advantage (they're generally worth several lesser cards) and with the right combos and a winning life total, they can secure a win. None of these cards will give a huge comeback (though a number of other good cards in the 4+ range can).

The big problem with this is that, as I stated yesterday, the big problem is that it really hurts card diversity. There's simply fewer gamechanger cards. Most people's ideas of what is great is an 8/8 creature. Hell, it's my idea of something great too. Almost any time I manage to get out something like that, I usually feel great because dealing with an 8/8 is very hard.

But that 8/8 or whatever is boring. There's less stuff that really just turns games around and Hearthstone becomes way more about boring trades.

So what should Blizzard do about it? At first I thought that they could adjust the way mana is gained in some way, but I think that's bad. I would like to see more alternative costs for things like sacrificing minions or discarding cards (like Warlock does already but with more interesting actual cards) and other similar things. I'd like to see more game winning stuff that is harder to play, but causes bigger swings if you manage to get it out. Imagine 10 mana cost, but requires you to sacrifice a minion in play. I think that'd be pretty cool and it wouldn't take away from Hearthstone's essential simplicity.