The number one problem with performance capture

No, it's not the so-called uncanny valley. The problem is the body language. Acting with performance capture is not the same as acting without, and unless you know what you do, it looks completely fake no matter how technologically advanced due to the human factor. Imagine some of the scenes (like the "welcome of Mars" scene) with live action characters instead, using exactly the same body language. It would just look weird.