Should Hearthstone add a "Legend Rule" mechanic?

Legendaries are supposed to be held back by the fact that you can only play one of them in your deck, which is why Blizzard makes them way stronger than your average card. With all the power creep that's been in the game though, the average good legendary can turn a game around completely - never mind multiple instances of it. We've seen tons of degenerate gameplay over the years with cards like Aman'thul, Yogg titan, Velarok, Unkilliax, the list goes on. All of them spring from the same problem: a card that is supposed to be only one of in your deck appears constantly, and with how easy tutoring is nowadays you don't have to worry about bricking.

Should Hearthstone add a counter mechanic to this? It would help balance class design better and cut down on uninteractive and solitaire gameplay. I don't want to be facing my 5th Aman'thul of the game, nor the 10th Unkilliax that can ruin my board and heal the opponent to full. I would like to put the spotlight especially on Unkilliax, as the lack of a graveyard mechanic made it a nightmare to face since with reborn just one instance of the minion (which could be cheated as early as turn 3) could be reborn dozens of times. I would personally like to see some changes in card design with the upcoming rotation since Breakdance, Shattered Reflections, Power Word: Synchronize and many more cards that allow such mechanics are going to rotate out, and I wouldn't like to see the likes of them again.