Vulcan is a planet with thinner atmosphere and a warm sun.

There are a lot of desertic areas and small seas.

If we use biology knowledge it would be logic to think Vulcan and Romulan would have a dark skin to protect them from sun.

In the series and movie the people from Vulcan are mostly white.

That does not make any sense.

https://memory-alpha.fandom.com/wiki/Ni%27Var