The problem as I see it, is two things.
1. community being divided via sharding of planets.
2. Apart from heroics, no obvious incentives for grouping. Perhaps if BioWare made the bonus exp while partying thing a little more obvious to players, then people might have a better understanding of the benefits of grouping.
There just isn't enough incentive for grouping or anything community based. Even RP seems restricted to the Cantina on RP servers.
What I struggle to understanding with the planet sharding, is they built these massive planets. For example Belsavis. Which are completely barren with only a 100 or so people on them, due to their sheer size.... it just seems pointless.