I heard Toriyama didnt write it
From what I understand GT was a TV series developed after the manga, so you can blame someone at Toei Entertainment probably. According to the Anime News Network the production staff consisted of:
- Series Director: Daisuke Nishio & Osamu Kasai
- Director: Minoru Okazaki
- Series Composition: Aya Matsui
- Screenplays by: Atsushi Maekawa, Aya Matsui, Daisuke Yajima, Junki Takegami (5 episodes), Masashi Kubota
- Original creator: Akira Toriyama
- Character Design: Katsuyoshi Nakatsuru
And over on the Dragon Ball wikia they describe Toriyama's involvement in the show as similar to his input for the DBZ TV series.
"This new series, called Dragon Ball GT (for "Grand Tour"), was a complete departure from the previous two anime series. Unlike those series, GT was not based on the Dragon Ball manga by Akira Toriyama. Instead, it was completely new material.... Akira Toriyama is credited as a writer of GT, and he strictly oversaw its production; this was the same process that was used during the production of the anime series Dragon Ball and Dragon Ball Z. He drew a rough design for the GT logo, he designed the GT appearance of the series main cast, and he designed the appearances of Giru and the GT spaceship used in the Black Star Dragon Ball Saga..."
That's the best information that I could quickly come up with. I know there are a few DB super-fans around this site, so perhaps they can fill in the details.