Kill La Kill's writing is great, you just have to understand what they were doing. Basically, the plot is about an edgy revenge anime whose destiny already got altered by Mako Mankanshoku - mistakenly seen as a Greek Choir, in reality, a deus ex machina who alters fate repeatedly.

So Mankanshoku Mako represents an author/fan self insert who fixes things for the protagonist - and Harime Nui represents people wanting edgy stuff and plot.

Rewatch the series with "Mankanshoku Mako alters fate" in mind and you'll see plenty of moments where she does. And rewatch the series with "Harimu Nui represents upholding and reinforcing fate" - you'll see a bunch of that too.