I'm not sure why you think that striving only to achieve business objectives could be considered to be a moral duty. Are you perhaps perhaps thinking of fiduciary duty?

If a company decides that technical development of engineers is good for retaining engineers and you as a manager refuse to do that, then no moral argument is going to help you when you get dinged in your performance review.

edit: Upon rereading the thread, I suspect that we may agree more than we disagree. My comment was directed at asknthrow's comment and I wanted to make the point (which other posters have more eloquently made in the meantime) that if technical development is part of your job as manager, you don't have a choice in the matter and your job is not just "to lead the team in the most effective direction in order to fulfil business objectives" (to quote asknthrow).

For sure. To be clear, I mean that regardless of what your bosses say you have an obligation to the people you manage. Obligations do not only run upward. (This is something bad managers often do not understand.)