Well, you did say that he'd be a perfect Terra because of it. =P
I can't agree with that, [I]especially[/I] in terms of what needs to be put into Terra's performance. Terra, as a character, is far more of a sympathetic figure than a cautionary one, and his voice should reflect that.
Terra's biggest motivation isn't the desire for the power that his darkness offers - it's his fear that he's some kind of monster because of the darkness in his heart. And [I]that's[/I] what I meant by vulnerability - Terra's horror at the consequences of his darkness, his need for validation that he [I]isn't[/I] a terrible person, and the underlying sense of hopelessness that leads him to clutch at whatever straws he can in his attempts to continue to be a good person.
And I can't say that much about Luke Skywalker since I've only seen the original trilogy once, but I will say that there's a lot more going on with Terra than the archetypical fight with the father part of the Hero's Journey.
I still think it'd be out of character for Disney's casting for Terra to have a more famous voice than Eraqus, though. Their modus operandi for everything is to get really distinctive voices for supporting characters (eg. Genie, Mufasa, Mushu, Ansem the Wise) and villains (Hades, Iago, Scar, Master Xehanort) while choosing less-familiar voices (if not less-familiar actors) for the protagonists themselves.
And I'd be much more worried about the result of a relative unknown playing Eraqus than one playing Terra. With Terra, it would probably just mean that whatever experience he had wasn't exactly mainstream - and I'd think there's actually some potential in choosing an actor for Terra from that kind of critic-bait drama (you know, the kind that's painful for normal people to watch because of all the emotional trauma). If Eraqus doesn't have a famous VA, though, they might saddle him with the standard Old Asian Martial Arts Master voice, and that would really bug me. =/
