It occurs to me that it's a category error to compare 2001 to today's sci-fi action blockbusters and say that it couldn't be made today, because it wasn't that kind of a film. It's totally the wrong comparison. There are still more thoughtful, intellectual, slow-paced SF films being made today; they're just independent films, like Moon, Primer, or if you go back a few years, Soderbergh's Solaris. So it's a complete falsehood to claim that no audiences or filmmakers today would be interested in a film like 2001. It might be valid to say that such a film would be unlikely to get made as a big-budget tentpole by a major studio such as MGM, though.
Head-scratching time traveling aside, Primer
has an detached, creepy atmosphere that really works for me. Sometimes low budget + creativity can work wonders.