Really good points. As for the point about Vitamin D and other things that could have helped, I suspect a concern was blunting the message that a worldwide pandemic needed a strong and widespread solution. FAR too many people were already mislead or misinformed about alternative treatments ranging from homeopathic products to animal wormers, and anything that blurred the message might have turned into talking points saying "see, all you need is megadoses of Vitamin D."
That being said, I wish medical practitioners had taken the opportunity of speaking about those things during their interactions with patients. Hell, even telling patients that cutting down on their pack a day habit might have been good for their lungs, especially with virus going around. I saw family members of people who have serious respiratory issues going outside the hospital and smoking like a chimney, and knew full well they probably smoke in their house without regard to the at risk relative.