Agree completely. Health care was about the most divisive major issue they could've picked, and one of the easiest to argue against (polemically). But inequality wasn't a buzzword in 2006/2007 when Obama's team was putting together its longterm policy plan (and according to Ron Suskind that process was a joke anyway). Inequality would've made a great platform-builder because it has tons of expert support and a lot of very obvious effects on a huge voting bloc's everyday lives. That's not to say the Democrats really had a "grand opportunity" ... they had the House, the Senate and the White House but that doesn't mean nearly as much as it used to. (cf. Dodd-Frank, which they managed to pass only nominally.) As far as tax policy, I'm not sure you can really create a debate about tax policy when, unfortunately, no one gives a shit (or if they do it's in the wrong direction).