I honestly don't think there is enough for a party of people to do right now. I can think of people going into Dregan's but there really isn't anything for a low or mid range to attempt on that kind of scale. I am probably asking for too much in mentioning quests but I do believe that party anything would be interesting to implement. Party buffs like the one just changed give a benefit to being in a party now at least. Now we just need fun things to do in parties! We already see a lack of places to hunt individually so maybe a party focused area would be a different solution to that. Mobs that require some kind of cure that a cleric has or a mob you need to sweep before it performs something. Just an idea.

Making certain classes important for combat situations would cause a need for parties and then it wouldn't make the parties too relevant, it just makes them relevant enough!