> The only explanation I've ever seen that adequately explains those curves is inflation. Inflation drives up prices, both of goods and of assets.

Actually, this disparity growth has been driven by the extremist anti-inflationary policies of the Federal Reserve Bank under Alan Greenspan and his successors. Reduced of inflation allows accumulated wealth to mean more over time, whereas higher inflation puts pressure on workers to demand (and obtain) wage increases and keeps the inequality in check.