TrueI think people don't like the new Bardock because it makes Goku less special.
Goku was supposed to be an aberration from the typical Saiyan nature. Now people will think Goku inherited his kindness from his father. Plus the whole idea that Raditz told Goku he was sent to Earth to destroy it and now he was sent there to keep him safe from Frieza.
Fans take retcons to heart because it fukks with what they knew or what they were originally originally told. The thing is, it doesn't have to be. Both things could be true. Goku being sent to Earth to destroy it from Raditz's view, just like he was sent to Earth from Bardock's view to protect him. Both things can still be true. The issue is alot of DB fans (and anime fans in general) lack any type of free thinking to be able to piece everything together. They need everything to be explicitly told to them, and if not then they're completely lost
And it's amazing that one line from Vegeta, which is a speculation at best caused an uproar. And in my opinion I felt like Vegeta was ridiculing Goku because he uses Goku is soft as an ongoing stigma.
Kindness isn't something you inherent. People are just dumb. And that wasn't what Vegeta meant when he said it. And even if he did, it's not factual.
Goku will still be Goku