I think some would benefit from knowing how to code. If they were programmers and turned into full-time managers, that's also okay.
I think it's mostly useful for managers of small teams, who are close enough to practical details for it to matter.
The CEO of a large company with 3 levels of management between her and the coders benefits less from knowing programming. Though she should understand the concepts and constraints, i.e. fast development vs maintainability.