Eccentric movement is the more seemingly passive component in resistance exercise. It's the reason a trainer will not you to want you to drop a barbell after a lift, or why a trainer will advise you to do, say, curls, 2 seconds up, 4 seconds down.
Depending on your fitness goals, it might be a good idea to pay attention to it. An academic article: Physiological and Neural Adaptations to Eccentric Exercise: Mechanisms and Considerations for Training.
For strength-building or maintenance, a little damage to muscle fibers is a good thing.