We have discussed it a lot, and I maintain that is not necessary because her only relevance to the narrative is to represent Shinichi's humanity. Knowing why she likes Shinichi or any of the other things that make up her character will make the romance feel more believable but does not help fulfill her role in the narrative. We don't need a romantic sub-plot because Parasyte's plot is plenty compelling on it's own and it would distract from it.

I pretty much disagree with everything you've said here. Let me start by saying a core belief I have in storytelling: well characterized, well-developed, and realistically behaving characters are always a good thing. I've never encountered a flat character that wouldn't have been better if fleshed out (there are limits with secondary characters though) and I've never encountered a fleshed-out character that would have been better if left flat. If giving a character good characterization and having them behave reasonably gets in the way of their role in the story, then the writer should likely rethink that character's role because there likely be used as a plot device and not portraying an actual character (which I believe to be inherently better).

In Parasyte's case I don't think giving Murano better characterization would have to get in the way of her role in the narrative at all. I think she would actually perform the role better if she had a personality.

I don't think Parasyte is pently compelling on it's own. It is somewhat compelling and an enjoyable watch, but it's far from the most compelling series I've seen. Moreover I think the biggest weakness in the series is it's bland cast. Shinichi and Reiko are good characters, but they're the only good ones in the entire series. Shinichi is not a strong enough character to carry the entire series on his own. Migi helps, but his personality doesn't really make the series more compelling. One or two more well characterized and interesting characters is exactly what this series needed to remain compelling in it's down time.

You say we don't need a romantic sub-plot (which I agree with you on), but in my opinion it already has a romantic subplot, it's just a shitty one. They should either make it a good one or cut it out entirely.

I keep mentioning the Tamura Reiko scene and it is now clear to me that is the most important scene in the show.

I actually agree with you that it's the most important scene in the show. I think it accomplished the macro narrative goal very well. In my opinion (and I realize I'm in the minority on this) it botched the micro-narrative goals. Shinichi's realization that he still has humanity felt very forced to me. That scene definitely could have been the start of the realization, but I think the process should have been more involved and it required a lot more inner dialogue to give that type of realization justice.

My opinion is pretty much the same on the Shinichi and Murano element of that scene. I agree it was a major turning point in their relationship, but that scene in itself wasn't enough to fully instigate the change. There needed to be a follow-up dialogue with Murano beyond "that's really Izumi-kun" for the progression of their relationship to be really compelling. I really believe that scene tried to accomplish too much at once, and while it could have worked just fine with follow-up scenes, they didn't pursue that route.

Also, this is a nice Tokyo Ghoul discussion we're having. ;)

Well I did use that Nishki scene as an example :P At this point I doubt anyone is going to follow our comment chain all the way down anyway.