Mostly because a vast amount of this game deosn't follow on par with the classes in the previous FF games. Also, because con have all the heals, revives, buffs. Leveling con all the NPC talk is about lif, healing, and nature. Level a THM and its al about assasination type kills, and you spill your own blood to gain power, you sacrafice your blood to heal others.
Now I can understand you may disagree with me saying it seems more applicable for thm=blm and con=whm. But to say "you dont see how people are getting confussed" might be a solid display that you yourself are confussed. Granted there is no teling which way the devs wil go. I find it difficult to understand how someone can state withsuch certainty that the class that sacrafices there blood to heal another, or sacrafices there blood for power, uses "damnation"(refering to hell) when con us "radiance"(A:to emit light or glow,B:marked by or expressive of love and happines)-from merriam webster.com.
So if you think the class that assinates, spills there blood in a rite to gain power, uses spells of dark magic to debilitate, uses hellish damnation as an attack , studies death to master its class, and uses resurrect(all sound very dark and necromantic to me), will be the healerr of white light or WHM, over the class that uses nature to heal, radiace to attack(sounds alot like holy to me), has all the beneficial buffs, and CURE. Then yes, I can understand how we confuss you.