It's really just because people have been waiting for this game for so long, and then it took so long in development, the anticipation is incredibly high and so people are freaking out at the slightest new thing i.e. the motorcycle and a talkative NPC. And they are feeding off the fact that we don't know much at all about those things, trying to claim the entire game is just gonna be those two things haha.
Anyone who was very excited about the game and now refuses to play it because of a motorcycle or an NPC is a clown, let's be honest. It's fine to not like those two things, but the game isn't called Metroid Prime: Motorcycle, or Metroid Prime: Talkative NPC, so people should stop freaking out so much.
Anyway it's all driven by content creators taking advantage of this to get views, and then people freak out because they see so many content creators talking about it so it feels like a big deal if you spend all your time in the social media world. It's just marketing so these people can get views, and be sensationalist and making people emotional is the best way to get extra views, especially if you are making them freak out about something. If you're an adult human being and can control your feelings, you're not freaking out about an NPC or a motorcycle haha, though you may say to yourself "I'm not sure those things will be a great part of the game".
It's not like Nintendo pokemon'd Prime 4 and put in zero effort to turn the franchise into shovelware haha, from what we've seen it looks like MP4 is going full on after being another epic Prime game.







