What's more, the more expensive (again usually actively managed) funds tend to have high turnover, and turnover implies a huge tax penalty for taxable investors in taxable accounts. So if anything, the winnings of lower-fee index funds are understated, as turnover-generated tax hits are not disclosed well.
I agree with the author completely - hopefully more disclosure, legislated, would entice more people to shop for lower-fee funds.
(Full disclosure, I run a startup that's based on helping people do index investing, so I might be biased ;p)