On some models it's optional, some come with a stock screen. AFAIK all gopros are capable of having a screen. It's a $40 add-on for models that don't come with one stock. I think part of the reason you see so many crappy gopro videos is because they are cheap (compared to any other 4k camera). People get the cheap camera and don't spend any time learning how to shoot and edit video.
As far as color balance issues and color palette selection, that is user error. Modern gopro cameras can record flat color palette, have a variety of ISO settings (up to 6400), manual color balance, manual exposure value correction, manual sharpness controls. They also shoot 4k30 or 2k60 or 1080p120, something even most dslr's don't do. I think it's an extremely reasonable feature set for a video camera that isn't at least dslr quality.
The one thing gopro lacks (afaik) is a remote trigger for external strobes when shooting stills.
I will say that shooting and editing video is difficult - especially underwater video. I don't think it has much to do with the camera model. I tried and gave up. Switched to a camera better suited (in my opinion) for still photography.
