I think part of the issue with the books' focus is that I gather Rodney is the writers' least favorite character in the main cast. (I have a kind of complicated history with the authors of these books; the short version is that I knew some of them in fandom for a little while.) I don't think any of them hate him, but for the most part they like writing the other characters better and also fall into the fannish camp of people who feel the show was too Rodney-centric towards the end, and I think that's got a lot to do with Rodney being shuffled offstage a lot of the time and mostly in a bad guy role. That said, I don't think they did terribly wrong by him in the books or anything -- well, I have no idea how the series ends, because I never read it all the way to the end -- but I think that's probably why it reads to you like it's rushing through the Rodney scenes.