I'd love to see discover phased out, but if it's going to stay, they should at least do some of the following:
1. Always make it "discover a card that didn't start in your deck" or "discover a card from a different class"
2. Remove legendaries from the discover pool. Then the 1-only aspect that makes legendaries unique can remain intact.
3. Actually put a reasonable stat cost on discover minions. A 2-drop with discover should be a 1/1 not a 2/3. A 3-drop with discover and mana discount should be a 1/3 or 2/2, not a 2/4. A 5-drop that discovers two spells probably shouldn't be a 4/4.