I see. Well, if I must...then I guess my take is that the number of classes can be more "narrow" with the great breadth of options of other layers (skills, archetypes, feats, backgrounds, themes, prestige classes...even, perhaps, things like fighting styles and arcane specialist schools as player choice-point/options) to differentiate the various special specialists of specfic specialities. Even to a point where one ranger or thief or mage may have very little to no resemblence to another beyond their signature -class-defining- features.
Yes. Agreed. Otherwise, why is it a class? If a Barbarian is just a Fighter who can "Berserker Rage" a couple of times a day...that's not really [worthy of] a class. That's a Fighter with a special feat or martial style.
By "narrow"...I am thinking a list for a particular system of...13 (minimum) to 24 or so. Anything beyond that can likely, or "should," be teased out through player options or "prestige class" add-ons.
So...breaking down by Warrior classes (the best at fighting), Wizard classes (the best with magic use), Rogue classes (the best at skills), and Mystic classes (the best at supporting/cross-discipline), we get a definitive class list that includes, at minimum:
- Fighter: default warrior archetype, Strength, defining feature: Combat Expertise (bonuses to hit and damage), battle stamina, extra attacks, physical save bonuses, situational interactive bonus
- Cavalier: specialist fighter, Str. & Cha. defining feature: Code of Honor, attack bonus, virtuous bonuses to various saves, defensive bonuses, horsemanship, battlefield attack & movement bonuses to allies
- Dungeoneer: specialist fighter, Str. & Int., defining feature: battle stamina, exploration skill bonuses, save bonuses, special monster lore & attack bonuses, limited Roguish Tricks.
- Barbarian: warrior archetype, Str & Con & third ability dependent on Clan chosen. defining feature: choice of Clan, damage bonus, battle stamina, Berserker Rage, Clan-dependent martial maneuvers/styles & skills.
- Martial Adept: warrior archetype, Str & Dex & Wis, defining feature: choice of Martial Style, attack bonuses, acrobatic stunts, save bonuses, movement bonuses, Style-dependent tricks/abilities.
- Cleric: default mystic archetype, Wisdom, defining feature: Channel [Divine] powers, Divine magic spell use, limited armor and weaponry.
- Templar: specialist cleric, Wis & Str. defining feature: Channel [Divine] powers, limited divine spell use, Smite mechanic (use spell slots), all armors, more/sacred weapons.
- Theurgist (Invoker): specialist cleric, Wis & Cha. defining feature: Channel [Divine] powers, Divine magic spell use, more channeling and better spell progression than other clerics, less armor & weapons
- Druid: mystic archetype, Wis & Con & Int, defining feature: Channel [Nature] powers, Nature magic spell use, limited armor and weapons.
- Bard: mystic archetype, Wis & Cha & Dex. defining feature: Channel [Nature] powers, limited-but-diverse spell use, roguish tricks, interactive bonuses, learned lore, limited armor and weapons.
- Mage: default wizard archetype, Intelligence, defining feature: Arcane Magic/Spell use, best spell progression, at will cantrips, spell attack/DC bonuses, lore/research bonuses, magic item use and creation.
- Illusionist: specialist mage, Int & Dex, defining feature: Illusion [Arcane] Magic/Spell use, Illusion magic spell list, at will cantrips, illusion/enchantment attack/DC bonuses, sneaky casting, other roguish tricks.
- Abjurist: specialist mage, Int & Cha, defining feature: Abjuration [Arcane] Magic/Spell use, Abjuration magic spell list, at will cantrips, abjuration/conjuration attack/DC bonuses, defensive casting, counter-spelling & banishing.
- Psychic: wizard archetype, Int & Con & third dependent on choice of Discipline, defining feature: Mental Powers, at will Talents, choice of Psychic Discipline, power point "casting"/manifestation system.
- Sentinel: a wizard archetype, Int & Str & Cha. defining feature: Bonded (magic) weapon, limited arcane magic spell use, enhance physical attacks & defense with magic, light & medium armors, martial weapons.
- Thief: default rogue archetype, Dexterity, defining feature: Skill Expertise, Roguish Tricks (accumulate more & quicker than other rogues), sneak attack, movement bonuses, dex/balance/reflex saves bonus.
- Acrobat: specialist Thief, Dex & Str. defining feature: Roguish Tricks, acrobatic stunts (offensive, defensive, utilitarian), movement bonuses, reflex/balance and thrown weapon bonuses.
- Rake: specialist thief, Dex & Cha. defining feature: Roguish Tricks, interaction and manipulation bonuses, lore, and sneak attacks.
- Ranger: rogue archetype, Dex & Str & Int, defining feature: Wilderness Expertise (bonuses to skills & attacks in chosen terrains), Hunter's Quarry/"Favored Foes," tracking, other Roguish Tricks.
- Alchemist: rogue archetype, Dex & Int & Wis, defining feature: Alchemy Expertise (bonuses to lore, identifying & crafting), potion/elixir making, poison/antitoxin identifying & use, enhance attacks & defense with magic concoctions, other Roguish Tricks.
Just about anything else can be handled through adding layers of options (whatever they may be).
Assassin? Anyone can be an assassin. Pick a class take appropriate feats, prestige class, special skills or theme package.
Spell-casting Ranger? Take appropriate feats, special skills or theme package.
Paladin? Take Fighter, Cleric, Templar or Cavalier (or, heck, maybe even Bard or Ranger or Sentinel). Take a simple 3-5 level Paladin "prestige class."
Swashbuckler? Take Fighter, Thief, Acrobat, Dungeoneer (or, heck, maybe even Bard or Sentinel). Take a simple 3-5 level Swashbuckler "prestige class."
Necromancer? Take Mage or Cleric or Aburist or Theurgist annnnd...Yup. Necromancer prestige class.
...and so on, ad nauseum.