Why not? It is a legitimate topic.
The Democrats have dropped the custom. Only the GOP has kept it up. With today's complex medical advances, you could well have the politicos debating scientific questions for which they are ill-trained in law school. We already have lawyers running everything and so I agree with the Democrats that we don't need additional legal debates on scientific issues such as personal health.
Reagan was one of the strongest men ever to be President. He was in excellent health but they attacked him on age.
As for Hillary, she may be in poor health and she is very old but let's see how she handles the issues. That is her Achilles' heel, if you want to get into anatomical shortcomings.
Does it take a village to decide a person's health?