I agree with you. I would see where some general Star Wars fans uninitiated to the NJO might be skittish about reading Invasion if they didn't know what was going on. Perhaps if the Invasion book had done a #0 issue that introduced the series and the major events up to the point where the story was. Also having a dramatis personae with the major NJO characters (pertaining to the Invasion story) at least might have helped too.
I agree too that the Lost Tribe audience interest was limited. I did enjoy the series though. I wouldn't mind seeing more Lost Tribe comics.