Have you tried playing a D&D campaign without a cleric in the party? What about an online game of Elder Scrolls without someone following an eso templar guide? Fought a dragon with only a squad of tanks, thinking each blow is but a scratch? The possibility is unsettling with the number of players, both tabletop and computer RPG, missing out on crucial setups in their group. And what could be the most important setup than a healing/buffing character?
This article describes the necessities of magical healing in RPGs – removing unnecessary down time it takes for cracked rib to heal, avoiding annoying penalties because you have a hole in your stomach and the like.