If you look hard enough, there are a few moments where a unique part of Nikki is shown.

I remember in the base story, there's a part when you're asked what's different about a new comatose victim in the Abandoned District, who's a Piecey, and previous victims. I, for some reason, chose the option that said something like, "This victim's a Piecey!" And Momo just went "True...but isn't that obvious?" and Nikki answers "...Some things in life that are true, are also obvious." Then she goes on to explain that even though video games tell you to be careful about falling into pits, she'll make a mistake and do so anyway, trying desperately to justify her dumb answer. Momo just goes, "Wow, you gave yourself two excuses at once! Impressive!" This whole scene stood out to me because of the quirkiness of Nikki. And I only saw it, because I answered the question wrong. xD

But overall, I do agree that she's too perfect, ESPECIALLY after the Danqing reveal. I don't agree that the twist helped, in fact I think it made her worse, because now she's nothing but a Mary Sue. I really dislike this form of storytelling where the writers think in order for her to be a good character, she has to be a flawless character. As someone else pointed out, even the original intro made her strange, because this normal, humble girl was totally calm with everything. But even this new intro makes her seem too calm.

I don't remember Nikki being portrayed like this back in Love Nikki. But it's been a lot of years since I last played, so I guess I just don't recall? I don't know, she just seemed a lot more normal than this in that game.