I'm not sure we've been that exceptionally good for awhile now. if ever. It's a story we grow up with, and tend to repeat, But i think the author has a reasonable assertion, and describes america pretty accurately. I look back at all the vitriole we would cast at peoples of foreign countries, and laugh at how beneath us they are. I suppose most countries feel that way about others, it's the age old iron-age in-group/out-group that we need to somehow grow out of. Frankly we, as americans, are now looking up at other peoples.
I see this response got down voted, but no one has given evidence to it mistakes. Compare America to most of the other 'modern' countries. Look at the metrics: Poverty, Health care, Social values, Life expectancy, Jailing practices, Murder rates... on and on.... where are we exceptionally good?