This is why they nerfed Pyroblast, Blizzard, Cone of Cold, Frost Nova.

What they nerfed is enough, and Hunter was unplayable for quite a while. Right now you can't really play delay mage that well, so the mechanic isn't really a very big problem right now. This is the reason why they nerfed it. Blizzard hates it too and they're working against it. There are ways to deal with it, it's just not very fun to play against. I do not agree with you when it comes to Hunters though. The Hero Power is relatively slow and you need to use minions to get your enemy to that point, and you can counter that in some ways.