A. We already have a term limit.

B. It was put in place to prevent another FDR, someone who was re-elected so much because he spent most of his political capital on actually helping Americans and then using the looming European and Pacific conflicts to build a middle class manufacturing economy. Which we promptly started selling for parts once the the rest of the world recovered enough to host our factories.

You could very easily argue that term limits were put in place to make sure no President could stay around long enough to prevent worker centric policies from being watered down or destroyed before they can have an impact.