It is one of those things that might be a good future use for a much more powerful device than current smartphones and a different world when it comes to connectivity. I suspect that for even the tiny percentage of S8 buyers that actually try to use it, the feature will be used once or twice at best to a) try it out, and b) brag about, then never used again.
This is about throwing feature lists against a wall, regardless of usefulness or capability. It didn't work out for windows phone, it is less likely to for Samsung.
The only way this would have a chance of working reasonably well with current tech is if all the phone did was provide the OS and apps. The dock would have to be a beast itself, with GPU, battery etc. that is, cost more than the bloody phone.