> but I can’t see how it’s defendable

Perhaps the key here is what YOU don't see, not the merit of the film.

2001 was ranked the 6th greatest movie of all time in the Sight and Sound poll, which is probably the world's most respected poll of industry professionals.

And it was ranked #1 by their poll of directors: https://www.bfi.org.uk/sight-and-sound/directors-100-greates...

Could it possibly be that these directors know something you don't?

For my own part, it's been my favorite movie since I first saw it in 1968 and I've probably seen it 20 times since then.