The initial intent of this thread was to approach this from the perspective of cooperation. This is a good goal, but requires a little effort (read this as a bit less hubris) on both ends of the spectrum. Unfortunately, it appears to be devolving into the age-old argument... and since the PLers don't usually care about the forums, it turns into PLer-bashing. 
People who brought suggestions to this thread mostly PL and RP at the same time, so there's no spectrum and no bashing here. Cooperation has been mentioned and is part of the solution. Yet game mechanics are another part, that cannot be dismissed. When, in the current unfinished state, a crafter or a healer spends 99% of his time bashing things to progress, he can hardly neglect that part in his RP. When everybody heals everybody, or mime, or make weapons, there's little reason to interact with chosen others; there's for example no place for a healer as a profession in PlaneShift. And because the mechanics are not there yet, it's totally opportune to debate on how to adjust them. There's still time to orient the mechanics towards a given purpose, and, for me, the 2 major purposes are characterisation and fun. There's an infinite number of ways to promote characterisation without hindering the pure PL aspect. In fact, it would probably improve it.
First, the character creation should mean something. 3 days after creation, a character hardly has anything in common with his past self, except for a name and a race. 3, 6 or 12 months later, he is just the same as the Lambda ulber-PC. The initial choices should influence the entire life of a PC. This is directly related to the inability to max everything.
Then, every step that improves RP is good for the community; setting, rules, player actions, all of it. To RP, people need a role to play, obviously. To level, one may just need the opportunity, but it also should be enjoyable. I repeat myself, but since much of what is needed is in the making (law enforcement, balance, new skills, etc.), I prefer to focus on what is already there and doesn't seem to do the job.
Btw, I'm not sure these PL purists exist; I've never met any.