My point is that currently a theme is just 2-3 feats. The problem is that most of these iconic classes have more than 2-3 iconic class features.
Lets take the ranger. The ranger was made to replicate Aragon. In order to do so, the ranger was given spells to replicate all the feature used expect of a travelling warrior since 1E-2E's skill system was weak. Between the class, skills, and spells; the ranger gained a lot of iconic ranger features. As the editions rolled, some became spell, others skills, and later powers. Slapping them back onto a fighter now as 3 feats would be impossible without also being unbalanced.
GX.Sigma
Exactly. The problem is the old 1-3E fighter was the guy who "uses weapons and are good at using them,".
The problem is that general concept of "any old fighty guy" was weak and underpowered. Even back then.
So the fighter evolved into "master fighty guy". And the rogue became "master skill guy". And the wizard became "master arcane caster" and the cleric "master divine caster"
With that done, the other former subclasses could have more a more aspects stripped away to make room for their iconic features. And at that point, the base class was no longer the root, it was another branch.
I'm starting to come around to your line of thinking. But then they'd have to define classes broadly enough to support a wide range of customization, but narrowly enough that they don't overlap. Which doesn't quite work yet:
Warriors
Fighter: Highly (conventionally) trained warrior.
Ranger: Unconventionally (perhaps self-) trained survivor/hunter.
Berserker/Barbarian: Untrained but powerful warrior.
Paladin: Highly (conventionally) trained warrior who also has divine powers and a code (??)
Warlord/Marshal: Highly (conventionally) trained warrior who's good at leading other warriors (??)
Rogues
Rogue: Sneaky, skilled, and/or charismatic rogue who can sneak attack.
Assassin_1: Sneaky, skilled rogue who can sneak attack (??)
Arcane Spellcasters
Wizard: Book-learned caster.
Sorcerer: Naturally talented caster.
Warlock: Deal-with-a-devil caster.
Divine Spellcasters
Cleric: Gains power from devotion to a chosen god, pantheon, religion, or philosophy.
Druid: Gains power from devotion to a chosen religion. (??)
Other
Assassin_2: Arcane rogue who uses shadow magic to sneak and kill.
Monk: Monastically trained martial artist.
Psionicist: Psionic power user.
Bard_1: Celtic warrior-poet who fights as a fighter and casts as a druid.
Bard_2: Arcane spellcaster-rogue.
If Assassin were a Rogue scheme and Druid were a Cleric domain, we'd be pretty close.