Answer:
David H. Freedman may have taken the approach of profiling John Ioannidis to make the problems with medical research more relatable and accessible to the general public. By focusing on the work and experiences of a single researcher, Freedman can provide concrete examples and anecdotes that illustrate the larger issues with medical research. Additionally, by profiling someone who has been a prominent critic of the field, Freedman can lend credibility to his arguments and give readers a sense that the issues he is discussing are important and deserving of attention. Finally, by presenting Ioannidis as a kind of "hero" who is fighting against the system, Freedman may be hoping to inspire others to get involved in advocating for change in the field of medical research.