You mean 1 life less than the old Warlock had after summoning his Dark Pact Slayer Blood Reaper.
While you might think that having 1 less life would make them comparable in toughness, getting to heal for an extra 2/round most of the time is huge, particularly when it stacks with Vampirism, Regenerate, and Death Link. While you probably don't need that much healing at once in a lot of situations (particularly for the mana cost), getting it for free adds hugely to the Arraxian Crown Warlock's survivability.
The Adramelech Warlock is the second squishiest mage in the game. All of the mages with 32 life except the Necromancer have a defensive ability that improves their survivability. The Wizard has Voltaric Shield, which drastically reduces incoming damage when combined with stacked Armor. The Priestess has Divine Reward, and will generally have quite a bit more than 32 life by the end of the game. The Forcemaster has a 7+ Defense. The Druid starts at 30 life, but can immediately get to 34 with Treebond, and effectively gets Regenerate 2 that stacks with other Regenerate effects while her tree survives.
The Adramelech Warlock has an ability that can be used defensively, but only if her opponent lights her on fire, which seems unlikely.