I'm going to assume you're talking about the dub there, and Ginga's voice is much better in the Japanese version so I guess you could watch that, I'm sure there are fansubs out there for a lot of episodes. But anyway an annoying dub voice isn't a valid reason to remove a character - it's a valid reason to get used to reading fan made subtitles. Responses based on the actual characters, not their voice acting, would provide more grounds for worthwhile discussion IMO.
Anyway I'll talk about the original series (where I actually prefer the dub to the original, partially due to being used to it and also because I legitimately enjoy a lot of the things they added).
Daichi. Tyson was an irritating lead character, we didn't need Tyson*1.5 - especially when that was accompanied by removing all of the more moderate (and interesting) characters from the main cast. Once Kai left the main team, as a kid, I lost interest in the series, and it was the last series I watched - and when I first watched it I skipped the whole world championships arc lol.
Hilary was annoying at first but when you don't really like Tyson you become ambivalent to her at the worst of times, though she definitely could be removed without impacting the series, and I personally think they could've at least added an actual female blader to the team instead of a glorified cheerleader.