Basically, this is a kind of Greek Tragedy-lite, Revenge of the Sith-style story where Bardock sees visions of a future he doesn't understand, visions of his son's accomplishments, and in his quest to figure them out and prevent tragedy, ends up causing everything to transpire exactly as he foresaw it. Now, probably the biggest thing holding it back is that, yeah, the Sayians probably did deserve everything they had coming to them; they had been genociding planet after planet for countless generations, and our own protagonist is so complicit that our introduction to him is his squad massacring civilians on some alien world. Yeah, he kinda realizes his mistakes, but he definitely doesn't go anywhere near atoning for them. I don't feel any sadness at what happens to him or any of the others.
But the story isn't expecting us to do so; it's not quite a condemnation of the Sayians like the show is, but it's certainly not sympathetic to them. And for something as dumb as Dragon Ball, I kind of appreciate that tiny bit of nuance. So, as far as Dragon Ball goes, this one's pretty good.
