All the cases you mention demonstrate that other fields employ methods of philosophy. Adorno gave it a name: instrumental logic.
Philosophy is about the methods, not the field or the results. Philosophy deals with the truth in statements and how to confirm said truth.
As someone with a Doctor of Philosophy...(not in Philosophy)...who studied the Philosophy of Science in great depth...the last thing I want to ever find out is that the credentials of the person operating on my kid....or who designed and built the bridge I am driving across....or tested the medicine I am ingesting....or is flying the plane I am in....are in Philosophy.
That said...I most certainly value, or at least potentially value (depending on how corrupted by political/ideological thought the faculty may be) an education in Philosophy with respect to critical thinking.
BTW...I would suggest that you were referring more to epistemology than Philosophy, writ large, in your last statement.