I don't think partying will be a big thing till after the job system is implemented. And I HOPE that they release quests that absolutely require a party to finish. They should also consider releasing low level quests that require a party to finish as well. They can prevent high level players from joining by introducing level sync like in XI...or just restrict that quest and only let players at a certain level participate (they cannot switch to a high level class during this quest).

But before all of that they should make it easy to actually form parties.