I like the fact that the main scenario quests are easy, though I think there should be minimal reward (other than story progression) for completing them because of this. The main scenario quests are good encouragement to continue with the less-engaging levelling aspect of the game. If they became a strong challenge to an inexperienced player or group (a la Chains of Promathia), then people may lose their drive to play altogether.

I'm not saying that I don't want difficult content. Side-quests are a fantastic opportunity to bring in some strategy-heavy team-based challenges and the rewards for successfully completing these should be much greater than what is received from Main Scenario quests (whether it be in gil or items). If there was a structured progression through said side-quests wherein completion of one opened up access to more, it would be all the more rewarding.

But yeah, keep the Main Scenario quests easy!