Go through the list of classes excluded. What were their 'roles' in EQ?
Warrior: highest defensive ability tank. Easily rolled into one of the 2 knight classes in Pantheon.
Mage: pets, dmg shields, summoned stuff, COTH. Again, easily rolled into wiz.
Necro: lifesteal magic, summon corpse, pets, mana battery. Enchanter & Dark Knight can split all these abilities.
Druid: snare... Grats Shaman
Bard: Jack of all trades buffer, limited CC. Can spread bard abilities between several classes to enrich them.
Monk: FD splitting. Won't be in game so it's moot.
Ranger: taking death touches, ranged combat. Just give rogues bow skills.
If I were to suggest one additional class added to Pantheon's list of 7, it'd be a ranged focused Ranger with a pet and snare. The rest of the axed classes are almost totally not needed.