Unfortunately in HS you need to choose between having fun or climbing ladder, the most fun i have playing hearthstone is in casual, any deck can win, you don't face the same shit over and over again (secret mage, warlock, aggro), but some people only enjoy playing the game if it means climbing the ladder and reaching the highest rank they can, because everyone has their playstyle and aggro is the fastest and easiest way to climb ladder, as someone who plays 1-4 matches a day casual seems to be the best mode for me
I think there should be a system incentivising playing off meta decks i.e. those including less-played cards. Each card could have a score based on popularity and then that could translate into greater experience gains or something else to encourage experimentation. They will not do it, not after they started introducing battle-ready decks but it would be a great way of rewarding experimentation.