Lack of stressors do make people complacent. That was one reason I liked working temp jobs: every job was a new location and a challenge. You never knew when the day would bring, in terms of challenges, and you were never on the same job long enough for complacency to set in - generally only long enough to cover some regular employee's vacation. After that, it was off to the next assignment.
Sometimes I miss those days.
You made a great point