When you take into consideration the fact that we've only seen the heirs of the rulers of the various realms, then sure being an heir may not seem like a big deal. But being an heir does make her special. She's in a position where she will eventually rule over the City of Aku (completely (though I'm not sure how the City of Aku is being ruled right now with Aku in retirement and everything)).
As for your analysis on Chi, I found it interesting.
I never really thought about Chi in that way. I agree that she is a character that is in development, and that she has indeed lived a very pampered life up til now (at least through demongo's eyes
). Thus far, I've felt that Chi was just a spoiled princess. As stated previously, she has led a very pampered lifestyle thus far, but I believe that that has only helped her become arrogant and develop both a sense of entitlement and some serious anger problems (especially when she doesn't get her way (see the interaction with Him for example (or even the instances where she's texting Mimi and not getting a response back)). Going back to the interaction with Him, she didn't hesitate to pull that gun on Him, at all. My take on that scene was that she did so because she thought that they were on equal footing. To me, this act was a sign of arrogance (seeing as to how she believed that she could take on one of the rulers of the Underworld with JUST a gun and bravado). It also showed how she felt that she was any information regarding Mimi. More evidence to her arrogance and entitlement issues happened later on
while she was speaking with Aku about the topic of matrimony. She wanted to speak with Him about marrying Mimi directly after threatening him (and shooting his hat off). After Aku leaves the room, she shoots off a string of anger-filled text messages. She even infiltrated another ruler's realm for more information regarding Mimi (more signs that she feels entitled to any information regarding Mimi). Thus far, this is my impression of Chi.
I don't think she feels out of place with regards to the other rulers, I sort of get the feeling that she thinks she can stand toe to toe with them (even though she obviously can't).
As for her feeling bad about not having her powers, I agree with what Tenshi said about it being a cool perk (mostly). She definitely wants them, but I do also see her as thinking that she needs them to get what (in this case who) she wants (Mimi). We really haven't been shown enough interaction between the two (between Aku and Chi(prior to Mimi's introduction to Chi)) to really know whether or not she feels bad about not having her powers yet. As of yet, it just looks like she wants them so that she can get her way (at least it does to me).
I'm not sure how I feel about the whole "Mimi is the chosen one" thing. We don't know the circumstances that led to her birth. Nor do we know how she came to live with Dexter & co. If indeed Blossom made some sort of deal with Him to have his child, but then backed out on it, that is what led to the war over Mimi. If she kept up her side of the deal, then would the fate of Megaville have been the same? If she never made the deal with Him, then what would have happened? How do we know that it was destined for Mimi to be here? Sure Dexter foreshadowed how great a risk it was having Mimi there, but could that have been avoided if they just handed her to Him (I know as heroes they wouldn't have, but still?)? Was there really no other choice but to have this war over Mimi? These are the questions I think about when I think about Mimi being a chosen one.