I think the problem could be solved with random loot that has a slight to moderate lean toward the skills and stats of party members.
What about the members that aren't currently in the party? Are you saying that the player will then have to drag along the party member they want to get loot? Those type of loot systems exist in many MMORPGs and are one of the aspects that are slowly killing them. Where is the fun in finding gear when everything you loot is always what you need? Why play at all?
Hence why I said a "slight to moderate lean" and not a "always gives you exactly the kind of loot you need." An absolutist philosophy isn't going to work here.
