The reason for the poor rating, says urban studies theorist Richard Florida in an interview with Fortune, is that "there's [a] widening gulf in the United States between the 'haves' and the 'have-nots' … brought on by "education and metropolitan zoning restrictions."
He explains that "inequality in New York City is like Swaziland. Miami's is like Zimbabwe, [and] Los Angeles is equivalent to Sri Lanka," adding that, "in the New York metro area, the 95th percentile makes $282,000 and the 20th percentile makes $23,000."
One reason major cities see such a wide wealth gap is that when new generations of workers cluster there, density increases and, therefore, so does property cost and competition.
"Companies are recognizing that talent is critical to their long-term success and that cities are the best place to find it," Bruce Nolop, former Pitney Bowes Inc. and E*Trade chief financial officer, and the author of "The Essential CFO: A Corporate Finance Playbook," tells The Wall Street Journal.
"Metropolitan areas offer ample opportunities to make lateral hires and are popular destinations for the millennial generation."
Not everyone agrees that wealth inequality is a problem.
Jim Iuorio, managing director of TJM Institutional Services, argues that it is vital to growing economies. "An economy that has no wealth inequality will, most certainly, stagnate and die, leaving widespread poverty behind," he says.
"We want and need the right amount of wealth inequality to fuel the creative ambition that leads people to seek a better financial future."
On the other hand, the benefits of that better financial future should be more fairly distributed, others say. "As a society gets richer, its citizens' living standards should rise," Lane Kenworthy, a sociology and political science professor at Harvard University, contends in a blog post. "The poorest needn't benefit the most; equal rates of improvement may be good enough.
"We might not even mind if the wealthiest benefit a bit more than other; a little increase in income inequality is hardly catastrophic," he says.
"But in a good society, those in the middle and at the bottom ought to benefit significantly from economic growth. When the country prospers, everyone should prosper."
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