Although New Capenna may have aligned better with the theme and design, the murders on Ravnica hold greater impact because they involve named characters that the community cares about, rather than individuals created solely to fulfill a narrative purpose.
I'm not really sure they succeeded there. Teysa's fine, Kylox was new, Tolsimir and Zegana, while established characters, never did anything to actually put themselves in memory, and Agrus just got stuffed in a jar to maybe show up again sometime later. There was little to no impact here, so they could've killed off a handful of New Capenna characters to the same effect.
The only major impact from this is that they went ahead and tacked on a reveal at
the end that Niv-Mizzet was ignoring it all to set up turning Ravnica into the center of the multiverse.