I would say that that is really a common theme throughout Kubrick's work, his characters are always a little distant, and most of the dialogue for the film seems to be going on inside their heads. Implication is the name of the game with Kubrick, I think.

However, when the veil is drawn back, like when Bowman is preparing to release himself from the pod to the bay, the nervousness on his face is tangible and paralyzing.

I think far too many films go overboard when expressing human emotion, and it makes me numb to any build-up after 2 hours of watching screaming faces and emotional writhing.

The lil snippets of Bowmans face when he is going through the "star gate" or whatever, and they are stills but crawling with pain and terror and awe, more emotion than has been present at any point in 2001, are really really really effective and hit me hard every time I watch this film. There's definitely some hint that this is what Kubrick thinks about humanity, in the cold, sober faces, and seeing them as reborn in face-peeling awe is really cathartic, and we never really get a glimpse of his, new, "evolved" humanity or what he thinks they would be.