>>16753320The thing is, from a conceptual standpoint it's not even a half-bad pairing idea (death and phoenix), but yeah whatever they had planned for this in their heads (I half-believe it was not just them making this up individually, but also somewhat corpo-mandated on them, seeing as how directly "takamori" was also pushed even by the official channels) didn't work out because they are simply not good enough actors for that type of character play.
Mori was supposed to be the "tsundere", but with her autismo she just came off as a grumpy bitch, and Kiara was overbearingly clingy to the point of desperation. And there's no resolution or development to it, you can only sit through so many repeats of "Caaaallieee mai wifeeee!!!" vs "ugh shut up kusotori!" before it gets stale and annoying, and in the end it was more a detriment and a hindrance to their characters because they were forced into a straightjacket role together and shipfags annoyed them when they wanted to branch out.
As for why in the first place, I guess they and/or management must've seen the relative success and fan engagement that "established" JP ships like NoeFure have and thought "yeah let's do the same thing and give them something like that right from the start!", completely missing the point (those successful examples worked because they developed organically over time and weren't just manufactured/mandated between people who can't make it work), and so they gave that role to the only two people who were conveniently in the same place together at that time for offcollab tete potential