I am going to guess Sega did not want to end up like the old Squaresoft games. Fighter classes would have Power, Hp, Defense and Evasion. No magic defense but enemies would still have to hit them 10 times with magic to kill them. Thus making all their fighter classes unstoppable.
Did the math on that one. I still should've died. When I fought Epsilon I only had 20 fire resistance and 1069 HP. Survived by 5.
Math turned out to be 1172 damage