In my ideal version of this series, I think Ahad and Glee would get their own book before Sieh got his.

I TOTALLY agree. My guess is that the third book wasn't written yet at the time the series sold and she couldn't get out of writing it as a trilogy. It certainly is the longest book, as she points out in her afterword.

Also, Jemisin's homicidal deities are more likable when observed by smitten mortals then when they speak for themselves; I assume that's deliberate.

So this ^^ - but it was in character, I thought.