EDIT: Whoops I think you might be talking about milling (forcing them to draw/over-draw in the HS sense) and not discarding from hand, which are very different things!
I was just using milling as an example since it's technically the only way in Hearthstone to make your enemy hero 'discard' their deck.
Thinking about it, if there was a card that made your opponent discard, the card was hidden, and they got to choose which one, I can see that working. As you said, that gives the other player control, which allows them to still play.
Overall, I'm just talking about how Blizzard wants Hearthstone to 'feel.' From not showing losses in your stats, how ranking is just simple stars, and how the only ranked reward each month is impossible not to get(outside of Legend) shows that they want this game to be easy and simple fun(For most people.) Giving players the ability to pick apart and destroy each other's deck, at least in my mind, is completely opposite of that philosophy. However, we both seem in agreement that play a card and random discards isn't a good thing.
However, I could see it working through a Loatheb-esc Battlecry or even a spell would work. Just have it be something that's kind of like tracking but for your opponent. Have them draw extra cards but they can only keep one. Could even have something where they draw three extra cards but have to discard two from their hand. More fun with milling!
No idea if these are even food ideas though. I'm not big on card games but it's actually a good thing to cycle through your deck faster. I wouldn't count it out, but I also see it highly unlikely.
