The last I checked, teeth aren't primarily cosmetic. Teeth are required. The healthiest things we can eat all require chewing: fresh/frozen vegetables, whole grains, lean meats. Without teeth, vegetables must be cooked to softness (losing nutritional value) or skipped altogether. Without teeth, whole grains are nearly impossible. The person I heard about consumes a great deal of pasta and sugared sodas. Even though she is often hungry, she turns down food that's offered to her because she can't eat it.
However, teeth do become cosmetic when someone is job hunting. The person I heard about is able to work - but has been turned down for countless jobs because she has no teeth. She can find work doing low-paying manual labor, but jobs that involve interacting with the public are off limits to her. Several potential employers have actually said flat out that they cannot hire her because she has no teeth and would not present a good face to the public.
If she were given false teeth, she could lose weight, find work, get her life back. Instead, she continues to need all kinds of assistance. This medicare decision leaves people at risk both in terms of health and employment.
Who makes these decisions? Probably someone with all their own teeth.