Well, with Japanese filmmakers tendency to completely change stories between the film any tv versions of shows (See Macross and Arrivederci Yamato) I was actually pleased at how well they stuck to the original storyline.
Honestly, Dessler/Deslock is a great character, and I don't think the film could have done him justice with only the few brief scenes the aliens were given in the movie. And turning over 15 minutes of the story to the Gamilas would have really hurt the plot. They made the right choice imo to keep the emphasis on the humans.
Thats all I'm sayin'.
I thought more people would have been upset about the ending.
Trivia: The voice of the Gamilas leader from the ending of the film was actually done by Desslers original voice actor. Plus look carefully at the crystaline humanoid figure that appears on the bridge. The profile looks very familiar.