Sanders explains his fundamental principles and how he can be expected to judge issues. Do you really prefer someone who either conceals his fundamental ideas or worse, doesn't have any? Are you better off not knowing a judge's views on freedom of speech, self defense, habeas corpus and privacy?
I like surprises as much as the next person, but not the legal kind like the Kelo and Obamacare decisions. These fiascoes might not have occurred if we knew the judges' views before they sat on the bench.