For 2001, the criticism guys brought up against Jurassic Park applies even more: take the FX out, what's left? The entire film disappears.
Well that doesn't amount to much because the story couldn't be filmed otherwise; there have to be effects because there were no space stations, moon shuttles, Jupiter-mission spacecraft etc.
2001 fails there completely. The film doesn't explain why things happen, it only shows that they happen. The result are beautiful but boring images and question, lots and lots of question which are never answered in the film (and which arise not only because the viewer falls asleep 45 minutes into the film).
Why the presumption that everything has to be -- or can be -- explained? There are many mysteries in real life that can't be explained, and I would think that the motivations or intentions of extraterrestrials would be one of the most unexplainable things of all. When the natives of the New World first encountered Europeans, did they understand maritime trade and the rise of the merchant class and mercantilist pressures for expanded commerce? Could they have even begun to understand that motivation? The viewer's position watching 2001
is an uninformed and questioning observer, as it would likely be in a real encounter with an alien civilization.
Film can tell stories visually and aurally, in ways the written word can't. The fact that a movie doesn't follow traditional narrative may not be to everyone's taste, but it shouldn't be cause for automatic dismissal.
As to boring images and viewers falling asleep, I would say 2001
's appearance high on lists like the AFI 100 and the Sight and Sound poll shows that some people manage to make it through the film awake and find something worthwhile.