There are probably lots of benefits from sun exposure besides vitamin D that we don't even know about yet. So I would agree with you.

But if you live anywhere in about the northern 2/3 of the US or above it is impossible to get much vitamin D from the sun during the winter. So it is either supplement, fly south for the winter (sounds good to me), or depend on the build up you get in summer months to carry you through to spring.

I agree Vitamin D supplement is not the best answer, but it may be the best available for a lot of people. Especially severely deficient people.

John