Having a strong core supports your spine and helps with balance. Both of these things are important for every individual with regard to activities of daily living, especially as we age.
In addition, the core focuses on numerous muscle groups–the abs, back, hips, and glutes–and you will see results faster than just working the abs with some crunches.
Furthermore, a strong core can both help prevent and alleviate some forms of back pain. Given that most people will have some sort of back issue in their lifetime, it’s worth it to spend time working the core muscles. Hope this helps!