And as for those other examples, I have yet to speak with any classic film fan who complains about the pacing of TMP, who also complains about the pacing of those other films you cite - especially 2001!
I think the pacing of TMP is fine, whereas 2001
is a crashing bore. Although that's probably because the slow parts of TMP have great music to listen to, while a lot of 2001
is just tedious silence. I've never liked the way Kubrick dealt with music.
I'm the opposite. 2001
is a masterpiece, my second favorite movie. The space scenes in the film come both with music and without, and the choice of which way to go, and then how to handle it, depends upon the tone of the scene. There's an incredible amount of tension in the scenes that are the quietest; one example that immediately comes to mind is reorienting the pod for the emergency space walk. The scenes making use of the Blue Danube are pure pleasure, and the Ligeti pieces are astonishing. But, 2001
provokes all kinds of reactions.