There absolutely are problems that require a more rigorous mathematical training than you get from undergraduate courses or day-to-day experience. Most data scientists and companies may not be tackling these problems, but they certainly exist.
Just having a PhD will open doors for you that would otherwise be shut. But before pursuing that degree, you should be confident that you enjoy working in the field and want to devote your career to it. Also, you have to be prepared to work hard, not just to get the degree, but then to land a job where you'll put that experience to use. Otherwise, you'll be sharing a cubicle with DataWorker and feeling like a fool.
That said, if you don't know whether you need a PhD, that means you probably don't know what kinds of problem you want to work on. And in that case, there's a good chance you'll end up working on a problem that only interests your advisor and nobody else (most PhD advisors have more students than they have good problems to work on). In that case, I wouldn't recommend it.
Just having a PhD will open doors for you that would otherwise be shut. But before pursuing that degree, you should be confident that you enjoy working in the field and want to devote your career to it. Also, you have to be prepared to work hard, not just to get the degree, but then to land a job where you'll put that experience to use. Otherwise, you'll be sharing a cubicle with DataWorker and feeling like a fool.
That said, if you don't know whether you need a PhD, that means you probably don't know what kinds of problem you want to work on. And in that case, there's a good chance you'll end up working on a problem that only interests your advisor and nobody else (most PhD advisors have more students than they have good problems to work on). In that case, I wouldn't recommend it.