Some kind of drafting system would be awesome. But having that doesn't mean cards should be inbalanced.
For example Heal just sucks. I cannot see any situation where it would be useful. Sure 10 HP helps but I would much rather take some other card instead because it's very easy for the opponent to do 10+ damage in 1 turn, making my Heal basically useless.
If Heal gave you 20 HP, it would be a much more balanced card. Then we could actually make decks where we have Heal.
So instead of asking "why should all the cards be balanced?", we should ask "Why not?"
