Star Blazers (AKA Space Battleship Yamato) was the first Japanese soap opera epic to make its way into Saturday Morning Cartoon programming. What Star Blazers, and its spiritual successor Macross brought was long storylines, complex characters, desperate situations and well rounded bad guys.
Oh, and the Wave Motion Gun, which is, in my opinion, one of the greatest sci fi ideas ever: a gun so powerful that it shuts down the space ship’s defenses for short time after use, making it a risky strategy whenever it’s used. A great storytelling element b/c its mere use was always going to be a desperate gambit, and thus, it heightened the tension of the climax every episode it was used. Nail biting stuff.