Indeed. XD I suppose for the same reason they wouldn't let you use Pheonix Down on Aerith or Soft on Red's dad. Seriously, Aerith died in seconds without a Phoenix Down but a character in your party dies? Oh, it's okay, they can wait, like, a bajillion years before getting resurrected and they'll be fine.
Plus 28 phoenix downs and the fact that I never give cure materia to one of the weakest characters in the game. I give Cure materias to people I KNOW will be in my party 90% of the time AND has the most HP & DEFENSE.