The uncanny valley is bad animation, nothing more, nothing less. Just because it's combined with high end graphics doesn't mean it's deeper. It's from a time of animatronics, those things produced awful animation.
In terms of CGI, I find that unrealistic lighting has a lot more to do with it nowadays. This is especially true in films. Computer generated humans tend to look like they're made of plastic, and it totally destroys any suspension of disbelief that may have existed.