Nope, have to disagree. That is actually an old idea/mechanic. It´s the same with bards in many fantasy universes. They often can boost the moral but usually that´s for the rest of the party only and not for the bard himself.
It would be bad design to call a perk charismatic nature if you can use it alone, because that would have nothing to do with charisma. So imo either keep it like it is or remove it.
I really don´t see any problem with one person having to put in points in MP. That´s normal for many perks when playing Coop that only one persons put´s points into it.