The unsundered werent free of suffering, they just swept it under the rug. That's why it's a fake utopia like pretty every other utopia in fiction. This is a recurring theme in fiction: look under the rug of any utopia and you will see its rotten core, the ancient's society is no different. The thing that this game celebrates isnt suffering, it's overcoming it. A real utopia is unachieveable but that doesnt mean we shouldnt strive to improve the lives of ourselves and others. Suffering doesnt stop existing just because we refuse to acknowledge it, this is why the ancients were doomed to fail and why hydaelyn took away their flawed perfection.