He's saying that the quality of life improvement provided by a coffee maker in 1960 consumed 0.6% of the typical 1960 middle class salary vs. 0.03% of a typical 2010 middle class salary. A 20x reduction in cost for the same quality of life improvement for the middle class, in this example.
I think it's easier to understand how much cheaper the coffee maker is today, both in terms of absolute price and what people can afford, if you translate it into today's dollars. "It would cost $221" is a lot more visceral than 0.6% of a putative generic annual salary.
One thing I added was "doing the math"; yummyfajitas didn't go that far (which is no reflection on his posting) ... plus I think it's useful to point out just how significant inflation has been over the years.
The value of the percentage metric is that it allows you to compare a certain benefit in terms of the work it took to obtain it at different times. Given 2000 hours/year of work, it would have taken 12 hours of work to buy a coffee maker in 1960 vs. 0.6 hours of work in 2010.
To me, this makes the comparison exceedingly easy to understand.