I would prefer quite the opposite to get rid of those slight existing differences and indeed have promos only as skin. This opens up adding future promos without having any balancing issues to consider.
If you have followed the path the project is heading towards, the apparent goal is to make the game more beginner-friendly and keep competitive pvp at a fair balance. That's why changes like the card charges or the upgrade requirements have been made, so to make the difference between players of varied time spent ingame less pronounced. A change purposely designed to disrupt that chosen balancing path of the devs and team sounds unreasonable to me.
