I realized that I was thinking about this wrong. If you were to add classes, it would almost have to be existing PHB classes, or hew very close to them. Hmm…I do think there is room for a class that cover similar ground to rangers and paladins with a couple “fighting style” type choices and a choice of one spell list, but…yeah idk. You may be right on.
Perhaps what I’d do is present an optional set of classes modeled on the core three, that are just as simple as these, but cover different ground, as an in between option that is openly and explicitly different from the core;
[Expert Killer] - your swashbuckler, assassin, sniper, or even your offense-first gladiator. High offense, less sturdy than anyone but the mage, mobile, good at chosen skills but less broadly skilled than Rogue. Sneak Attack combined with a choice between Backstab, Bold Strokes, Challenge, or Ambush. Basically fighting styles for a “rogue like” class.
Rogue - The skill monkey. Covers the thief, bard, gets less expertise but more skills and Jack of all trades, sneak attack but little offense beyond that, very good damage mitigation but not beefy.
Guardian - Heavy fighter, knight, gets fighting style and weapon spec. Very similar to your fighter.
Mage - Your generalist wizard, no healing, blows things up and does weird stuff.
Priest or White Mage - Imagine a class that encompasses only the non-warrior cleric and Druid archetypes.
Paragon - Ranger/Paladin, for those players who really don’t like choosing between broad categories, and would always pick Elf in HeroQuest.
