People percieve Minus as taking away everything that made Bardock interesting and watering down Goku's backstory.
I don't think it's the hellspawn many make it out to be, but I do think it's uninteresting and too vague at points, raising more questions than answering.
My least favorite bit is the implication that Goku is nice because his mother is nice. It just says none of what Goku learned from grandpa Gohan matters and even if the headbump happened, that wouldn't matter, either. He's nice by nature, not because of the circumstances he grew up in. That's some "Naruto is the child of destiny" crap.
The silver lining to that is that the story is so vague about it. It never actually directly says Goku is nice because of Gine and Raditz is pretty rough, so it could entirely be that he just didn't actually remember anything because the pod's programming still did it's trick. Goku's Saiyan nature shows through in a lot of scenes in the current story. Just because a parent shares traits with him doesn't mean he's completely like that. You can easily read it like that which is why Minus makes so many people angry, but his headbump was never actually retconned.
You could do something interesting with this. You can turn the whole thing on it's head and say that Goku is only good because of grandpa Gohan's teachings and the influence and Bulma and co, not his headbump.
The movie looks to be having the theme of the environment shaping a person. So that would be a excellent way to actually give some resonence to the story. Bardock and Gine being bland nobodies gets a different meaning, which is that they're just bland nobodies and thus Goku is a low class nobody.
The second bit is of course Bardock being a bland character. This one, I don't care much about. The special was never something Toriyama wrote. So it's just irrelevant here. I like it a bunch more than Minus, but Minus is doing it's own thing separate from it so I judge it as such. The Minus version of Bardock is just the typical rough dude turned good by his pure waifu trope, which is boring as hell, imo. Gine being a pure housewife character is boring as hell, too. I think it's sexist, too, but putting that aside, mostly just boring. Goku coming from a bloodthirsty race and turning into a good guy from the influence of the people around him is actually interesting. This undermines this idea, but at least it doesn't dissapprove it like I see many people claim it does.
Reading comprehension is a nice thing.
The only thing you need to do to fix this is to show that those around him still did influence him. Nothing else really matters.