There are lots of ways to tap creatures without attacking these days, and granting a whole creature type undying is enough to do more than just swing combat in your favor and give you insurance on board wipes
Atarkas Command deals 3 damage to each opponent
It is a card that has almost as much value in the graveyard as in your hand and enhances the effect of other cards in your deck like Fact or Fiction while de-powering some offensive disruption from your opponent such as a Blightning
On the other hand, there are certain decks (those overloaded with cheap removal, like Rogues and Auras) that can be tough to beat because we only have 16 creatures, and the rest of our deck is dependent on keeping those creatures on the battlefield
That could be an Elesh Norn, Grand Cenobite or Avacyn, Angel of Hope you're popping into play for the low price of 3 mana and bouncing a tapped creature back to your hand, which is possibly additional upside with the right ETB creatures