"Research indicates that high (income) inequality reverberates through societies on multiple levels, correlating with, if not causing, more crime, less happiness, poorer mental and physical health, less racial harmony, and less civic and political participation. Tax policy and social-welfare programs, then, take on importance far beyond determining how much income people hold onto."
This isn't surprising. To see what's surprising, check out where the U.S. of part of A. ranks in life expectancy and what's happened to income inequality since the late 1970s.