This question evaluates your work ethic. Most recruiters recognize that evaluating your work style and ethic only after being hired is often too late. But gauging your level of preparedness for your interview gives them the insights they need. By displaying how above and beyond you've gone to prepare for your interview will clue them in your work ethic. Showcasing your enthusiasm for this opportunity will give them insights into the attitude you'll bring with you to the job. Showing up under prepared, and winging your interview will inform them you'll likely put in the bare minimum on the job, and are only interest in the money and benefits they'd have to offer.