To identify a person's strengths, ask: "What was the best day at work you've had in the past three months?" Find out what they were doing and why they enjoyed it so much. To identify a person's weakness, just invert the question: 'What was the worst day you've had at work in the past three months?" Then probe for details about what they were doing and why it grated on them so much.
What you should ask for and expect from your employees is high job commitment. Commitment works a lot harder than loyalty, and gets more done than morale does. Commitment energizes. it empowers. It inspires creativity and pulls a person's true potential into play. That's crucial because organizations can't get by anymore with mediocre performers. Organizations can't afford to carry dead weight or accept half-hearted effort by employees.
It's not the data - it's the insights and capabilities derived from it. You can give two people the same raw information, and one will see the patterns, the anomalies, and the defining insights. The other will not.