There could be something to what you say. 

One line of thinking is that when Vitamin D increases through sun exposure, the body is actually doing it to protect the skin.

At least one doctor I follow thinks the lower level of viral disease problems associated with elevated vitamin D levels is just a correlation rather than a causation. In other words he thinks maybe the low vitamin D levels and the higher associated viral problems (poor outcomes with covid and viral flu's) is more of an indication of poor metabolic health rather than the vitamin D levels actually preventing the poor outcomes of the diseases. One reason he thinks this is because vitamin D supplementation has not shown such huge improvements as it appears it would. He is all for healthy sun exposure because he thinks it has other health benefits that we just have not discovered yet, but he questions the value of the raised vitamin D levels done in an artificial manner.

He thinks the body produces the high Vitamin D levels with sun exposure as a protection mechanism to help protect the skin.

That is doctor Paul Mason out of Australia. I don't remember which specific talk he talks about this, but it will be one of these that comes up in a search.

https://www.youtube.com/results?search_query=dr+paul+mason+sun+exposure

Edit: here is the 5 minute talk that most people will have the time to listen to:  https://www.youtube.com/watch?v=NVqNO8rgYKk