All of these things, such as never seeing Tobias tell the others about his family, not seeing what happened to Alloran, not getting answers to half the questions raised leads me to the conclusion that as good as Animorphs was at setting things up, it was terrible at resolving them.
Maybe if more time had been put toward resolving unanswered questions and less toward how best to destroy every relationship, accomplishment (other than ending the war), and goal in the series, that wouldn't have happened.