I've played a handful of MMORPGS in my time and FFXI was one of them. I really enjoyed the grouping and small community feeling of the game. After a while I found it harder and harder to find groups within a half decent time limit. Which made the game almost impossible to play because you can't find people to help you. On the flip side there are games like WoW. 95% of the time I don't even bother with groups because I can do it alone. Which makes for a lonely run to the level cap. I've always wanted to see a clear solution to the problem, or attempting to see a balance come into effect with solo and group play.
I was thinking about the FFXI system and it's pros and cons about how it goes about it. The job system alone is by far the biggest contributor to group play(IMO) It made it simple to level other jobs without having to make a whole new character and lose out on all the quest rewards or crafting skills you have obtained. Meaning you were contributing a body to more leveling groups.
I found many more cons then pros. Cons being some jobs we're considered inferior and would have a harder time getting groups. The level gaps in partys reduced experience points obtained overall and with a 75 level span it greatly reduces the chance of discovering 6 people to work together. The standard group make up had too many players.
So I was tossing around a couple ideas to the effect of lowering the level cap. If you had a level cap of 100 and 1000 players on. That's a rough estimate of 10 players per level. If you had 1000 players with a 20 level cap. That's 50 players per level. Naturally you remove those not wanting to group, or crafting, or questing and you have more potential for groups at the lower level cap then the higher one. It also increases the opportunity to find people near your own level for maximum EXP gains.
Another idea would be a reward system. Like they had for the Promy quests at the crags. You got an experience scroll used on any job for it. Everyone likes rewards. No good deed should go unrewarded. It makes people less likely to help. Which in turn decreases grouping.
My last idea would be smaller groups. Say HALF the size they were in XI. 6 Players is nice and all, but I think 3-4 would be about optimum. Tank, Damage, Heal/Support. Three or four total rolls don't need to be duplicated into 6 slots. Which again, increases your chance of finding a complete group instead of desperately spamming for that last group member.
And finally, my last point...is that I wish I had a smaller post to present my ideas. This much reading will probably lead to less people actually reading the whole post.