The Ph.D is not “more academic” simply by virtue of common perception. By it’s very structure and intent, it is traditionally the degree required for professional academic employment. There is nothing anti-ecclesiastical about it. A Doctor of Philosophy is one who simultaneously becomes an expert in a particular area of research within the broader domain of their discipline, but also becomes, or at least is supposed to become a philosopher of their discipline - to gain a knowledge and understanding that transcends mere knowledge of the literature and key contributors. Students in a Ph.D program thus necessarily take courses in theory, first and foremost. Other classes taken are merely for the purposes of gaining background in areas related to dissertation work.
I admittedly do not know much about the Doctor of Sacred Theology degree. You say it is very similar to the Ph.D. That may well be true. But by definition, as I have explained, a Ph.D is academic. It is for the purpose of becoming an expert and a “philosopher”, and original contributor. You quite literally become a doctor of the philosophy of your chosen discipline. The Latin root of ‘doctor’ suggests someone who has the authority in their subject to teach and write, making ‘doctor’ and ‘professor’ inextricably linked. The S.T.D degree however, though having the title ‘doctor’ is, in my understanding, primarily for the purposes of filling an ecclesiastical office.
The Ph.D then, is the more orthodox academic degree, that by definition is scholastic, while the S.T.D, though having a strong, rigorous academic component, is religious in nature. If the S.T.D is similar, it has modeled itself on the Ph.D.
I don’t know why I just wrote an essay on this. As if it really matters, haha.