Main story quests also give a lot of exp as well, and importantly unlock certain gameplay and content elements (Inn rooms and levequests/guildhests by completing the level 10 story quest , airships and the Vlybrand-Aldenard ferry with the level 15 story quest, retainers with the level 17 quest, personal mounts at 20 etc). Main Story quests can be identified by a special Meteor icon above the relevant NPC instead of the usual exclamation mark in a speech bubble.