The WCIV novel and game don't exactly follow the same path. They both end up at more or less the same point, but there are some differences in how they reach that point.
As others have mentioned, there were plenty of aces in WCP. I'd guess that at least a third of the Devil Rays are "Devil Ray Aces". Apparently the Nephilim belong to the anime school of thought when assigning fighters - i.e. give your best pilots the super fighter. Considering how much better than everything else the Devil Ray is, I can't say I blame them.
Or it could be that only Devil Ray pilots last long enough to rate a distinction from the regular pilots.
Now there was a distinct lack of Nephilim personalities, but that made sense from a story standpoint. Maybe if the third part of the Prophecy story is ever told, we'll get to meet some bugs.
Bugs are predictable? How so? I can honestly say that I can only think of two other sci-fi stories that feature bug-like creatures in starfighters - and one of them came AFTER Prophecy - Freespace.
The other story is Orson Scott Card's "Ender's Game", and in that story, the Formic starfighters are not really essential to the story.
Starfire (and its related novels by David Weber) feature bug-like creatures and starfighters, but the Arachnids themselves never actually fly fighters.