The work-energy principle is often preferred over Newton's laws for analyzing the motion of rigid body systems due to its simplicity in certain scenarios. Both principles are valid, as they rely on the conservation of momentum and energy. However, the work-energy approach can streamline problem-solving by focusing on energy changes rather than forces. This can lead to more straightforward calculations in complex systems. Ultimately, the choice between these methods depends on the specific problem context and the ease of application.