That brownish purple maskerading as a shade of black is a dreadful colour. Makes it so much easier to swallow the upgrade cost for any other colour.
And that's precisely what VW want you to do and why they have opted for a standard ('free') colour that won't be popular with the majority of customers; most people will pay extra for an alternative colour.
More profit for VW, as it probably costs no more to paint a car in one of the 'extra-cost' colours than it does to paint it Black Rubin - all will get primer, colour coat and lacquer. Oryx White may be the exception, as I believe there's an extra step in the painting process.