A suggestion which I feel would be interesting and have little to no damage to either the economy etc. only providing a better experience for new players and keeping the grind more focused and engaging.
Example:
Level 80 - Beginner Warrior Quest
Kill 500 monsters in X
Kill Boss X (might require help from friends/group)
Reward: TDB Book, Class Armour, Class Weapon
Level 100 - Novice Warrior Quest
Kill 500 monsters in X
Kill Boss X
Reward: FireFrenzy,Class Armour, Class Weapon
Level 110 - Skilled Warrior Quest
Kill 500 monsters in X
Kill XYZ
Reward: 5mil, Class Armour
Level 120 - Legendary Warrior Quest
Kill 500 monsters in X
Kill XYZ
Reward: 10mil, Class Weapon
Level 130 - Master Warrior Quest
Kill 500 monsters in X
Kill XYZ
Reward: BattleCharge/SamuraiTraining etc, Class Armour
All examples to give you an understanding of how each question may offer you something you're looking for/need for that class.
Example:
Level 80 - Beginner Warrior Quest
Kill 500 monsters in X
Kill Boss X (might require help from friends/group)
Reward: TDB Book, Class Armour, Class Weapon
Level 100 - Novice Warrior Quest
Kill 500 monsters in X
Kill Boss X
Reward: FireFrenzy,Class Armour, Class Weapon
Level 110 - Skilled Warrior Quest
Kill 500 monsters in X
Kill XYZ
Reward: 5mil, Class Armour
Level 120 - Legendary Warrior Quest
Kill 500 monsters in X
Kill XYZ
Reward: 10mil, Class Weapon
Level 130 - Master Warrior Quest
Kill 500 monsters in X
Kill XYZ
Reward: BattleCharge/SamuraiTraining etc, Class Armour
All examples to give you an understanding of how each question may offer you something you're looking for/need for that class.