Most people who want that much detail, buy an Action Camera. That's the niche they have carved out...detailed and smooth video of whatever thing they are recording. I look at my Dash Camera as being something my wife (if she even remembers it is there) can use to provide evidence that I was killed by a vehicle and prove the color, model and even license plate number. For that kind of use, you don't need much resolution.
You also run into a problem with providing a SD card that is fast enough. When I bought my HaloCam, I was dropping a lot of frames or getting only half a frame. My SD card was supposedly "fast", but not really. It wasn't fast enough to transfer the data of two cameras, sound and GPS data all at the same time. Now if I had problems with two cameras that recorded only 1080...what would it be like for two cameras to be recording at 4K? They may not have SD cards fast enough.
When I first bought my Sena 10C, I thought I'd post videos of my rides. I didn't. If you want the video online, you have to pay for someone to store it for you. It takes a lot of time to edit and trim videos. And after glancing at the video, most people don't look at it again. I've found it far easier to use my Sena 10C to take individual photos to post and share.
Chris