I look at the "strength" aspect of wisdom and charisma as sperate things.
WISDOM - Willpower. In a postive sense high WIS is mental fortitude in a negative sense it is stubborness.
CHARISMA - Ego. In a positive sense high CHA is confidence, in a negative sense it is recklessness.
High WIS Low CHA - The ultimate self appointed "expert" who may or may not know about a topic but will refuse to concede his position.
High CHA Low WIS - A party boy/girl. You never know what this zany person will do next. But it will be big!
So how does this relate to magic? Sorcery is the ability to control reality around you. Wisdom has little to do with this as you are not resisting the forces of chaos, you are controling them. Intelligence has little to do with it, as it is an intutive process much like breathing (however, like breathing, advanced techniques can be aquired). Charisma helps a lot because your ability to control reality is a given, but your sense of self versus what you want to change is pure ego.
Lightning will flash from your hands not because you invoked the proper incantation, but because you command the lightning to flow and what is it compared to you?
