Stereotypes yes, but that's part of the flavor of a race.
No one is quibbling that. You've established that elven arcane arches and gnome illusionists and dwarven dwarven defenders are flavorful.

You haven't established why a human arcane archer or nezumi illusionists or Goliath defender isn't flavorful and needs to be prevented.

Because all you're doing is something that can be applied to any PrC. Humans and Dwarves probably make more thematic ruby knight vindicators than high elves or gnomes, but the devs didn't feel the need to slap a "no gnomes allowed" tag on the class.