Plato’s The Republic: An Ideal Society?

Could Plato's ideal society work in the modern-day USA?
Probably not, but let's explore it a bit.
In The Republic, Plato claimed that each person is born with innate traits that, if pursued, would be their natural calling. For example, individuals showing strong leadership ability could be military leaders or politicians. Or, if a person was a natural caregiver, they should be in the medical field. In every case, we all must seek the Form of the Good; anything less was like living in a manipulated reality.
Plato claimed we should expose our children to various experiences and learn what suits them best early on. He divided his Utopia into three major factions: Guardians, Workers, and Philosophers. I appreciate the idea that we all have a purpose, have strength, and can all positively contribute to society. But, I'm skeptical that such rigid social roles, determined at a young age, would satisfy the thirst for liberty and unlimited freedom so proudly held by an American.
Plato's philosophy can appear cold, dismissive, and rhetorical and undoubtedly exhibits a kind of certainty in the belief that logic supersedes all emotions.
But, I see one element of human nature that hinders all Utopian societies: our thirst to evolve and destroy. When it comes to evolution, the mind is strong, and individuals always seek to preserve themselves over their fellow man.
Plato recognized that his Utopia was theoretical because virtue and vice are continually at war in each of us. We evolve out of childhood into a personal hell trying to satisfy our urges. As a result, our virtues and vices play games with each other and cloud our reason.
Even in The Republic, Plato rationalized lying over truth-telling to preserve the State. But, could Plato be right that if we control this balance, we would maintain humanity and exist in a perfect Utopia?
Are we, at least in the West, living in a failed Utopia because we have been unable to find that inner harmony that will lead to a just life?
Plato appears to be operating on the premise that only gloom and doom can be an outcome with any utopia where humanity is involved because we lack reason and wisdom. Plato claimed democracy was a popularity contest and only a just ruler could deliver us from our vices. But under a less-than-just ruler with absolute power, the system can corrupt absolutely.
If Plato's thoughts on Utopia are to be followed, we must remember that one element of human nature is not extinguished too quickly: thirst for knowledge.
How do we extinguish the flame of hate and ignorance and ignite the flame of social welfare for the betterment of our own sake?