If Normal and Savage mode shared the exact same mechanics (with damage being the only difference), then hardcore (maybe even some/most midcore) players would get pretty bored of Savage really damn quickly. Heck, it could potentially make it so Savage is cleared within a day :T
Am I exaggerating? Most likely, but there's a reason why SE made Story mode easy (Binding Coil of Bahamut. Fantastic story, but at the time of its release, only some could experience it).
