The floor is open for debate. Personally, I think the first two points say it all:
- “Vitamin” D is not a vitamin; it is a hormone synthesized by the action of sunlight on skin. For this reason alone, it does not belong on the food label. (and may I add: it doesn’t belong in food, either! – Marlene_
- Vitamin D fortification must be understood as a form of hormone replacement therapy. As such, it raises questions about efficacy, dose, and side effects that should be asked about all such therapies.
Food Politics » FDA’s food label proposals: comments on Vitamin D.
Marlene Dotterer 
I have to admit, I never thought of vit D that way, but you are right. High doses are prescribed a lot up here in Alaska, where we get almost no sunlight for long periods during the winter. How to handle the issue is a great question, and one I will have to personally think about.