Having just read the novel, I think they should have been background characters in DOTM. It wouldn't have affected the story and running time, but then we could have seen their deaths by SP. Skids saving BB and Mudflap attacking SP would have redeemed them a bit after ROTF. It would have been good to see what happened to them, instead of them just dissappearing from the trilogy. I'm sure some people would have cheered when they died from the cosmic rust!