> Anyway, the point is our porn does have plot.

I can see is and this is exactly the problem. As long as it's just a porn without plot, it's fine as long as it is fun. But once you have a plot, it has to make some sense. And it doesn't feel like it does.
> there was a new TSAB 'downsizing' policy

But it didn't explain why such a policy was introduced, why it had to be killing mages, not just firing them, and why they are going along with it even if they feel utterly sad about it. But that was okay as long as it could be considered porn without plot. The reader would just assume the answer to all these questions is hentai logic. But then the next parts come out and the third part's main purpose is to give characters reason to willingly die... which declares that in this story characters actually need a proper reason to willingly die, which means hentai logic doesn't apply in this story, which means first part suddenly doesn't make any sense anymore.