In some ways it would not surprise me to find out that the antagonists are so flat because the author is writing all her personal nemeses into the books. The mix of real-world-esque nastiness and lack of nuance really reads that way. That know-it-all jerkass who always talked over the girls in grad school? YOU'RE AN EVIL RAPIST TRAITOR NOW, BUDDY. The teacher who always had it in for her? You will be in this series FOREVER just so I can have the heroine throw buckets of cold water on you and everyone comment on how evil you are!

.... etc.

Anyway, I feel as if not reading any further in the series is a case of "bullet dodged."