Providing quick gameplay benefits, they can help turn the tide in your favor
It seems impossible to play the classic blue tempo deck in Modern these days, but a deck full of Hookblade Veteran and other cheap assassins in blue running Escape Detection, Flare of Denial and other cheap interaction cards seems tempting if probably futile
Thats the sort of deck I want to build
But the above subtlety has nothing to do with the source of the draw effect
The utility of being mana rocks with built-in card draw makes them a strong choice for many decks
But if we can find a home for it across multiple packets then we could print more versions and itd stay true to our rules of rarity. So, as a low power card with an ability that triggers on death, Nocturnal Feeder works well for the Minions packs, but by giving making it a Vampire and Rogue type, Wizards were also able to slot into those themes, too