I mean is it hard to balance? yes
IS the UI a problem?
No it can even stay like it is. Ther was already a solution postet to that:
SO out of all the try hard modes… why is ther not even an brawl or a real try for an 2on2 mode?
I mean imp what hearthstone is lacking most is the social interaction with a friend.
Going into a voice with your friend building strategies for new combos?
Finally to be able to play full heal / full tank ect?
Maybe they could even have own cards, or other balance changes.
But to be able to play with a friend or even 2 against 2 or 3 others would be a dream come true