How about a test? Here are three icons who I think we can agree fit certain assumptions of high stats.
High Intelligence - Bill Gates
High Wisdom - The Dalai Lama
High Charisma - Bill Clinton
Who do you think would be best able to get through the following spells? Who's least?
1. I cast suggestion, and tell them to run as far away as they can.
2. I cast dragonfear, and roar at them to try to scare them into fleeing.
3. I cast hallucinatory terrain, and try to convince them the building is on fire so they'll flee.
My answers
[sblock]The Dalai Lama isn't easily swayed by my suggestion, nor does he panic in the face of magical fear. He might not think to question the spontaneous combustion of a building, though, and would probably run from that.
Bill Gates isn't particularly resistant to compulsion or fear magic, but he's clever enough to be skeptical of the sudden fire. He knows what's possible, and as long as his mind isn't being affected, he can reason out when things are wrong.
Bill Clinton, well, he might recognize the suggestion, and know not to listen to it, because he's persuaded people plenty in his time. But dragon roar? He'd run from that. Fire too.
At least in my opinion, this shows that Int works for illusions, Wis for charm or fear, and Cha for charm only.[/sblock]