esram is a workaround for the slower DDR3 ram, it is part of the design to compensate for the bandwidth restrictions gained by using DDR3.
As a seperate memory pool, it has it's own advantages on top of boosting theoretical total system memory bandwidth, a couple of devs on B3D have given insights into the kinds of things a seperate memory pool can offer..
But, I'm also inclined to think that the 30fps foibles being reported on PS4 could well be chalked down to unoptimised code, but then this doesn't quite jive with the 'Xbox One development is 6 months behind + their tools suck' stories that have been 'confirmed', or the "Sony first party devs are gods'..
Personnaly, I think that they had 'targets' and 60fps just isn't one of those for whatever reason, I don't remotely think MS are suddenly so clever as to have known Sony first parties where targetting 30 and so went for 60 to make a point because I'm not seeing them make a huge song and dance about it..