I'm not sure why Wookies would necessarily need to be innately intimidating. Consider this:
The representation of Intimidation in the rules is linked to Coerce and Willpower. Wookies don't inherently use Intimidation in their culture. Why not? Because they aren't concerned with such sophisticated methods of communication. They just get mad and cut to the chase.
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In these scenarios, we can see how a character being afraid of a Wookie has nothing to do with the Wookie using Coerce. The character is innately afraid of the Wookie because he knows the Wookie will rip his head off in a fit of rage - which is linked to the Wookie's low Willpower. This isn't Coercion. It's just a fact of life.
Coercion is used as a conversation point. You're trying to bend the will of someone else to your liking. Wookies don't do this at all. Of course, it is fair to say that when a Wookie is in rage, it is very prone to causing fear to all witnessing parties. But that's balanced out in the nature of combat. If you aren't smart enough to figure out that you should run away from a 7'5", 400 lb death machine in the heat of battle... you're either too terrified to respond, or you want to die. Running away in this manner is still not Coercion, though. It is just a natural fear mechanic of battle.
You guys are seeing a flaw in the system, and all I see is something that makes perfect sense. Wookie is as Wookie does.
I think Raice nailed it. Coercion is about psychological finesse, figuring out a person's pressure points and applying just the right amount of pressure to make them compliant. It's why the law enforcement NPCs have this skill while most of the fearsome brutes do not. Wookiees don't need to bother with finesse, they just need to be scary enough to trigger the fear mechanic and pass a few boost dice to the interrogator.
And with regard to Wookiee fearlessness, I don't think they're inherently courageous. I think they just have more experience with fearsome creatures and violent situations, which reduces the difficulty of any fear checks they may encounter.
Case in point, a howling dianoga in a trash compactor sends a century-old wookiee whimpering down the hall, while his human partner dismisses it with a hip shot. Wookiees seem to be fearless right up to the point they encounter something that doesn't have any limbs to tear off.