1) They are highly subjective
2) They are inevitably incomplete
3) They give a false impression of order of importance
4) Little great literature takes the form of lists
5) Despite their importance, the Ten Commandments are just a small part of the Bible
6) You almost always forget something
7) You sometimes repeat yourself (see 2 and 6)
8) They're adolescent (see Nick Hornby)
9) They are pretentious - "Ten greatest albums of all time" - yeah, right!!!
10) I can never think of the right number of things to fill the list.