Charisma is about PR image.
Not arguing the definition of the charisma, let us just agree on the main point: charisma means personal attractiveness, interestingness, influence, charm, magnetism, appeal.
Look at the today's leaders, and tell: which politician is charismatic? Who is a real leader?
What impression do you get from looking at Palestinian Chairman Mahmoud Abbas (Abu Mazen) or Lebanon's Prime Minister Fuad Siniora? Can you call them charismatic leaders?
When you see them on TV, you think something is wrong with them. You see them hide themselves and their real feelings behind their glasses, or behind the expression of their look. Compare it with the open expression of other Arab leaders like Egyptian president Hosni Mubarak or Hamas PM Ismail Haniya.
One choosing to support not-charismatic politicians has some non-clear reason for that.