Back in Fallout, charismatic/speech characters could work miracles. They could talk the Master into giving up his world domination. In FOnline, they're kind of a wet blanket. Their strengths apply to the number of followers, mercs nobody buys, and that's it. So, here's my plan:
Having someone of significantly above average charisma, say 7 or above, combined with a decent speech skill (80%?), as leader of your party has a positive effect on the rest of the team. The higher the charisma/speech the bigger the benefit. Much like the 'leader' perk in Fallout Tactics where they gain bonuses to agility and armour class. These guys would improve their team's rolls - to hit, maybe even a small bonus to critical chance/critical strength, that kind of thing.