The biggest problem with Miles Edgeworth: Investigations. (The first one)
In retrospect, the main reason this game's story is the least interesting is that the central plot is thematically superficial.
To put it simply: the story is about Edgeworth dealing with a smuggling ring across his cases—and that’s all. There isn't anything particularly personal or compelling driving the plot, aside from the flashback case or the Yatagarasu plot twist.
It’s not that I wanted stakes that were intensely personal or massive character development for Miles—at least not in this specific game. Rather, I wish the game had made us care more about the consequences of the smuggling and counterfeiting in Zheng Fa (beyond Lang's perspective).
I think Kay is the character they should have given a thematic arc—specifically, one centered on "the desire for revenge and its consequences." Basically, she could have harbored a deep-seated grudge against Calisto Yew—one that grew and became more apparent as the investigation unfolded.
Then, once Shin-na is cornered and holding a gun, Kay could have snatched the weapon away in a sudden move and poiting it at her. That would have been a high-tension turning point for her: if she chose not shoot, she’d be letting her father’s murderer go; but if she did shoot, she’d be permanently branded as a murderer, just like the woman she hated.
Edgeworth and Gumshoe would try to talk some sense into her so she wouldn't ruin her life, while she struggled to suppress her own thirst for vengeance... until she remembered her father's promises and finally relented.
Doing this would also mean changing Calisto Yew's character and ditching that lame "No-Identity Spy" twist. Her connection to Cece Yew should have been real—meaning she killed out of a genuine desire for revenge. That would have created a perfect contrast between her and Kay.
But those are just my ideas. What are yours? And what do you think is the game's biggest problem? (I still liked it, though.)