Please consider making any hero available in the Hero Academy purchasable in the shop. Here’s how it might work: pick a random hero from the aforementioned set, and make it available in the shop for a few days each month. I recently mentioned in a comment on this forum that there should be some area of the game that offered a sure thing to players willing to pay. I think this would go a long way towards mitigating the frustrations a lot of us face in the game.
I should add that this feature would mostly be targeting new whales, a fraction of a fraction of the player base. It would be expensive to purchase one of these heroes. This would not dramatically change the nature of the game.