I think this actually discourages RP, and promotes cliques. High levels staying away from lowbies and to themselves, and no longer seeking out new people/lowbies at the Outskirts or other above mentioned lowbie areas.
While not everyone cares that much about exp, progression is still a natural part of the game, due to the dnd system used in nwn.
Solo-ing or dungeoneering is more appealing to many high levels with this than seek out people to RP with and meet, amongst the lowbie areas.
Or even some areas used by high levels like Degannwy, that is still closeby the lowbie areas, with lowbies travelling through.