The increasing gap between players and bosses.

If we are talking about lowering the gap between funded and unfunded in the context that the unfunded can be in parties. Why not add party only skills. As in you need a hero +paladin to uses this super uber-damage move. or have like a skill that reads out " if you have 6 party members increase your Matt & att buy 300 or +10% resistance for every party member" or something ridiculous like that. It promotes partying a lot of people and creates an atmosphere in which unfunded can take down harder tier bosses because they gain damage or class survivability they need to survive. As unfunded players dont care about being stronger than others but simply being able to complete the task.

That is what I had in mind, much like how you got a bonus if you had all the classes when doing the Orbis PQ. To encourage but not force partying varying bonuses could also be given for all Adventurer/all Heroes/all Resistance parties and the like since each group has at least one character that can crash and would add to the fun of figuring out how to beat a boss with the set-up you have instead of just picking whoever's strongest.