A degree is not required for the ATP. However, in pursuing a career as an ATP-certificated pilot, a degree may be a valuable asset. Any degree, but obviously one related to the aviation industry may be a wiser choice than, say, interior design or art history.
Speaking as an educator, a degree is a credential that primarily attests to your ability to begin and finish something on time and with specific effort. The same can be attested by your PPL, CPL, and eventually ATP. So the question is, what does an academic degree give you on top of your FAA certificates?
Well, an academic degree could give you the experience of socializing with adults outside your immediate family (if you are fresh out of high school), the ability to evaluate sources of information, the analytical skills that lay the foundation of problem-solving, and communication skills that are essential for advancement as a professional and an individual.
In other words, higher education prepares you to be something bigger than just a pilot, an accountant, a historian, an engineer, etc. It gives you the skills and the tools to be a steward of the republic -- I know it sounds idealistic but that's how it is.
As you advance in your career you may find yourself in positions of increased responsibility and authority. You will need strong communication skills. These skills are not part of your PPL or ATP training. You learn how to communicate effectively during the general education portion of your college studies.
You will also need good quantitative skills: anything from budget planning to performance reviews requires math. Again, this is something that you learn in college. Business methodology is also something you learn in college. I don't think the CPL knowledge test asks you about the difference between op ex and cap ex.
Down the road, you may find yourself on a career track that can benefit from an MBA or a JD. And your employer may, or may not, support you in pursuing these degrees.
These days we are contemplating the future of employment, in light of increased automation. Higher education is in an identity crisis, trying to figure out how to exist in a future when vocational training may no longer be relevant. And that's why I stroke an idealistic tone earlier: in such a vocation-less future, well-educated stewards of the republic can make the difference between a thriving society and a dystopian one.