Chekov was created to appeal to fans of The Monkees. Chekov bears a resemblance to Davy Jones. The Chekov appeasing the Soviets thing is just Roddenberry press puffery.
That's what I've always heard as well. When my daughter first saw Chekov in a TOS rerun she flipped out and thought it was Davy Jones for a second. Then he spoke and killed it for her.