I am trying this experiment right now. I did a batch of concord wine with the skins on and it's a nice burgandy/purple color. There were a few more grapes left on the vines so we picked those and wondered what it would be like if we removed the skins from them and made the wine that way. To be honost I thought that it would be almost a white wine because the inside of my concords are green. Well I just started it yesterday and the must is almost a brownish color. It still smells just as good as the other batch but the color might not be that attractive. Oh well, it's worth a shot. Maybe someone else here has tried something similar and can chime in.
As with most fruit, a lot of flavor is in the skins.
When pressing grapes you will get white juice no matter
the colour of the grapes.
When fermenting on the skins more colour, flavor, sugar, acid, etc will be extracted.
Some ingredients (like tannin) will dissolve better in alcohol as in water, so by fermenting there will be extracted more of them.
My Mother likes concord white. It was the first wine I ever made when I was 10. I had a neat Grandfather. Said I needed to learn how and we lived in the middle of 300 acres of Concords. You will need to add a little more sugar to the white.