The obliques are underrated. If they're tight, everything else can be affected. Your obliques are responsible for both good hip function and shoulder function. If they're not able to do their job correctly, you'll experience a loss of strength, loss of performance and, in some cases, nagging pains that soon become injuries.
This stretch can help improve shoulder mobility, leg length discrepancies, and chronic lower back pain. Even if you have none of these issues, doing this stretch at the start and end of your workout will get you more mobile and help with recovery.