I completely agree. Percentiles are a very unintuitive way of thinking for this sort of data. It's really easy to know how much one made last year, but it takes a while to figure out what percentile one's income was in. Differences in Percentile vs differences in Income is even harder.

I felt strongly about this the moment I read the article on NYTimes - I reproduced the data set to the best extent I could and actually went about plotting against absolute income:

https://docs.google.com/spreadsheets/d/1jD87QN3pPZjoefrAm4E_...

That's a far more intuitive chart, that a lot of us will understand better. I also graphed how much these children actually go on to earn against absolute income. I compared these results in a blog post - http://unside.t4you.in/data/intuitive-axes/

HTH.