There's no denying that Chiaki panders to a target demographic, but I don't think that precludes her from being a good character at all. She ended up being a pretty interesting character full of quirks, and she had an intriguing backstory that made her stand out from other panderish-type characters. And her video game references were amazing; I love how she tried to work them into the various awful situations they were in.
Because she was at her best when she's making blatant, over the top gaming references. I only wish they made her throw out
more video-game references.
unfortunately Chiaki fell from A+ to F- when they revealed she was an AI
Except her characterization absolutely necessitated it. There was something off about Chiaki from them moment you met see her; it wasn't enough that she was ridiculously cute and a savant at video games, but she was also
incredibly sharp and cool-headed. Inhuman competency doesn't even begin to describe her; She never truly expressed fear or doubt. She was completely selfless. She was one of the main driving forces behind the trials, and could easily come up with conclusions despite being in a high stress situation (there's a clear struggle with Hajime, and he doesn't discover everything as a result. Nagito is just a freak). She also had absolute faith in the other Ultimates, but without a clear reason.
Chiaki: You’re not that kind of person, are you? You’re not the kind of person who could hurt someone else, right? It’s all right ... you’re okay ... everything’s all right...
It goes way beyond sheer altruism, and it makes perfect sense once you clear the game. I thought chapter 4 practically gave it away when
she wasn't suffering from the effects of food deprivation whatsoever. Add in the fact that her long pauses are most likely related to her *loading* information, and you have a character that was pretty clearly intended to be inhuman from the start. You can't have that kind of character without a strong justification. Even Kyoko had several moments of weakness in DR1. As an advanced AI, she justifiably has full knowledge of the students, general intelligence, the ability to keep a calm head at all times, and not being burdened by human emotions.
You can hate the twist, but her character is completely ridiculous without it.