For most of the rest of the Babylon 5 spin off that would be correct. But Babylon 5: In the Beginning
did well as it was an interesting story tying the various episodes that flashbacked to the Earth-Minbari War and providing the rest of the story.
Yamato 2199 has some of that presently as well. Some flashbacks to first contact. Some about the Second Battle of Mars (that would be interesting to see, since that was were the Earth stop Gamilas). Scenes with Kodai's brother, Sanada, and Niimi during the early days of the war. Kodai's family getting caught in a planet bomb. Yamamoto's brother. Yurisha's arrival. The terrorist (maybe) bombing that put her in a coma. The Fleet's last sortie before the Battle at Pluto as they leave in 2198. And the start of construction of Yamato and maybe even the choice to build the Wave Motion Gun.