If I go apply for a job, I have to provide information about my past experience, and if I am being considered seriously, I often have to take a drug test and undergo a full background check, including a credit check. I'll be judged not just for my skills, but also for how I'll "fit in" to the environment. And all this is for a job in which I would have no guarantee of continued employment.
So why should a Supreme Court nominee be exempt from having to provide any information whatsoever about his qualifications and views for a job that's a lifetime appointment?