And because unlike Breath Weapon, Incite Emotion can be used for attacks, maneuvers and blocks at skill+2. The full potential of Incite Emotion is summarized below;
Someone with Superb Intimidate and Incite Fear + Lasting Fear can rip your mind to shreds, doing Epic attacks at Weapon 2. Or they can make you cower in terror, unable to think of anything to do - that's an Epic offensive Block against your Discipline - or make themselves so terrifying you fear to attack them - that's an Epic defensive block against your attacks. Even a wizard with superb discipline is going to get mauled by something like that. And don't forget all the aspects they can apply to others - and themselves. They can do maneuvers that very nearly automatically succeed against most people to apply sticky aspects like "cowering", "fleeing in terror", "fainted", and any other nasty, fear-related thing you can think of as well as put on themselves sticky aspects like "frightening", "intimidating", "dreadful presence" and so on, which they can tag on social rolls (duh), defense rolls (you fear to attack them), attack rolls (your fear of them is a weakness), and of course further uses of the Incite Emotion power itself since an emotion-related aspect that matches the emotion of the Incite power is only going to help.
Same thing can be done with pretty much any emotion - though Despair is more offensive than Fear in general, while Lust is more socially oriented and defensive. After all, who would want to attack the sex-goddess they are busy drooling over? That their inability to attack (or socially engage, depending on the situation) comes from a Legendary+1 block made by tagging an "unnaturally attractive" aspect she'd previously created on herself via maneuver in order to enhance her use if Incite Emotion to create said block is kind of lost on them; you can't read the fine print when you're busy making a fool of yourself.
There's a reason Incite Emotion + Lasting Emotion is priced as much as Channeling.