This isn't a new line from Summers or Obama--the former laid it out in his last Financial Times column before joining the administration--but I thought Summers hit it really well in today's speech:

Bubble driven economic growth is problematic because of disruption and dislocation – affecting those who took part in the bubble’s excesses and those who did not.  And, it is not entirely healthy even while it lasts.  Between 2000 and 2007 – a period of solid aggregate economic growth – the typical working-age household saw their income decline by nearly $2000. The decline in middle-class incomes even as the incomes of the top 1% skyrocketed has a number of causes, but one of them is surely rising asset prices and the fact that financial sector profits exploded to the point to where they represented 40% of all corporate profits in 2006. 

--Noam Scheiber