Well, I am not a nutritionist, but I am a Registered Nurse (non-active). There are many reasons patients get drinks like Ensure. There are many different types of supplemental drinks used to treat individual needs of the patient.

 It's a more complicated issue than I think the nutritionist is addressing. Yes, food is the first medicine, and we would all do better eating quality natural food. However, many patients I have cared for cannot eat, or process, natural food.
FWIW, in Nursing School, we had to drink some of those adult supplements that we give to our patients. I even drank some Pedialyte that we give to kids. Most of my patients did not get those drink supplements, but if a doctor ordered them, there was always a good reason. I was OK with that.
Having said all that, I always felt that we learned very little about nutrition in Nursing School. Just the bare minimum to get through the NCLEX testing. Should we know more about nutrition, I think so. But, in reality, the patients we care for temporarily in the hospital need specific care for immediate needs. Good nutrition is a longer strategy for a healthy life. That was not usually my concern for a patient on a day-to-day care basis.