It isn’t, the deck is actually really strong. I used to play it wothout Zeph, and in the value based matchups (priest, mage) it really makes the difference.

For a lot of reasons: it cost less so is more easy to play on curve and gain tempo (spend 2 play on 3, rather than spend 3 and on turn 4 develop a 1 cost minion), you can tutor specific target that are more relevant for your gameplan than “the lowest cost minion” and then sinergies are way more stronger.
Diving Gryphon become a 7/4 assault and draw another assault card.
Phase Stalker become a 5/6, harder to remove from the board and can easily trigger his ability more than once.
Tutor one of these cards mean you cycle throug your deck, increasing his consistency.
Can tutor Zixor, both normal and prime, with the latter being almost a game winning combo with 4 7/7 rush on board.
A simple stonetusk boar will be a 4/4 charge for 1 mana.
Hyppogriph (a card never seen in the meta and now in hig legend HH decks) will be a 5/9 rush taunt for 4 mana.

A lot better then an oversized Murmy

I don’t play wild, but Baku should be a solid legendary to have anyway in your collection. Try Odd Pala or Odd Rogue, they were OP back in the days, and you will surely found it useful in the future, when more strong odd cards will be release!

“Unjustly” it’s not correct. Every class has his strenght and weakness, or his “identity” as they keep calling it.
Wich is DH identity? It has heals, draws, card generation, aoe, cheap hero power (it was the reason you played an even deck back in the days), strong small minions, tokens, strong big minions, mana cheating, card generation, rush minions, outcast, combo OTK potential and can IGNORE TAUNT.
How can it be an healthy and balanced class?