Creatures you control can boast twice during each of your turns rather than once
And in Commander, Lifelink often scales into something even sillier, where one big swing can potentially undo several turns' worth of game actions, all while immediately triggering a half-dozen life gain payoffs
WotC has even rested the concept, releasing recent major sets with no serialized cards to let the market breathe.
Id happily run this if my deck cared about auras or enchantments
Its got a win-more feel to it, but the cost reduction is a welcome addition to dragon decks, which usually have very high curves
They enable big turns and protect fragile commanders so players are able to have more fun doing their thing, and printing them in precons means the average player will have access to this vital effect