I'm very happy to hear you enjoy the game.
I also couldn't agree more with your comment on the game balancing, and it's something I wish I had a bit more time to spend on, and is definitely one of the first things I would want to improve. I think you're right about the dragon being overpowered, though I feel like it may be that monsters with high attack are significantly more powerful than the others, and is something I would need to consider in the future.