As an academic, I am well aware of the difficulties involved in using the terminology “Old Testament.” The technical term for the problem presented by this terminology is Supersessionism, roughly the idea that the “New” Testament has done away with the need for the “Old.” I am also well aware that other terminology is available, such as Hebrew Bible, Hebrew Scriptures, and TaNaKh. It should be pointed out that each of these terms have their own sets of difficulties, e.g. the whole of the corpus is not written in Hebrew and Law, Prophets, and Writings (TaNaKh) reflect a particular ordering that is not shared by the Greek (which was used by Jews for some time) and subsequently Christian versions of the corpus.
Yet this is not the primary reason for settling on the terminology “Old Testament” on this site. My reason for using the terminology is a pragmatic one. If I went with my preference, I would probably use “Hebrew Bible”; however, when comparing the search terms “Old Testament” and “Hebrew Bible” on Google, one finds that “Old Testament” gets 368,000 searches per month and “Hebrew Bible” gets only 74,000. My thought pattern was simply that if I wanted to try to educate the most people possible about this corpus of literature, “Old Testament” would be the best terminology. My hope is that those who visit the site and decide to make use of many of the free courses will become acquainted with this issue and become better educated about these writings. However, in using another term, these listeners would probably never reach this site in the first place.
If you would like to learn more on this issue, you may want to check out the introductory lecture in the course The Hebrew Bible by Lawrence Schiffman, which is free with a trial of Audible: