Kubrick intentionally left questions unanswered in 2001, and some of us like it that way. It works as mysterious, technological eye candy, with an excellent soundtrack. For many it stimulated the imagination. Others hated the film for the same reasons. Kubrick noted that children tended like 2001, but not so much their parents. His theory was children in 1968 were raised with cartoons and other visual stimulation on TV, whereas their parents were more accustomed to radio and books.
2010 was entirely the work of Clarke. Kubrick had nothing to do with it. Clarke explained everything in his book, 2001, and tied up loose ends in 2010. So I don't find it surprising that people like either 2001 or 2010, but not both.
'cept me. I even liked the follow up novel "2061".