Just to start by saying just how awesome it is to have Josh back and these kind of great threads
Now i'm completely down with the uncanny valley thing, i've been talking about that in many dev type threads down the years and it is one of the many reasons i'm not a AAA gamer these days, too much effort on making humans that don't look quite right, and actually pull you out of the immersion you are hoping to get from a game.
Some history, this is quite recent, probably only the last 5-6 years or so in games. Before that characters looked abstract enough (due to graphical technology limitations) to never look human enough to cause the uncanny valley problems. And i think this is where to aim for if you want to make 'human' like faces in your games to avoid that issue. And yes that does sound counter intuitive (why make non life-like looking humans when the tech can support that).
I'll talk about Elite: Dangerous for a second. One of that games huge problems currently (and it has many) is the lack of 'personality' it exudes, which in turn leads to a rather flat and sterile/lonely feeling when playing. Neither Frontier (elite II) or FFE (elite III) suffered from that to the same extent because they both simulated human faces in the game which added that important psychological connection to the game world in the players mind.
Now it can be argued that Frontier achieved it better than FFE because FFE used FMV and fairly poorly acted real humans! Frontier used a semi-procedural method that drew faces in typical pixel art from that era (so not that realistic!). And it worked perfectly in giving enough of a human face to space to make it feel 'alive' and not sterile/lonely.
As human beings we are keyed from birth to read a human face and that is a strong part of our dna, which effects many other things in life. So i would suggest, looking at the above examples (of Frontier, FFE and Elite: Dangerous) for guides on how to apporach this if you wanted to?
I would also add that even a 'simple' silhouette can work quite effectively here, in adding that human feel to a game.