I'm A Banana
Potassium-Rich
Your premise is faulty.
That's not my premise, that's me explaining why the idea that worrying first about the "core four" classes isn't really a problem. Folks said it was. The only time I could think of that it was was in 3e, where we had classes like the Swashbuckler ("Like the Fighter, but sucks more").
Is there another point at which people think designing the "core four" classes first hurt the game? Certainly pre-3e didn't have that problem (quite the reverse actually, new classes tended to be MORE powerful than before). If 3e didn't have that problem, either, then I guess, well, we've never had that problem? So then the fear is also unfounded in that way?