I hear what you're saying and I agree with your ideals on the subject, but I really can't imagine Rockets being offered in more than just two or three colours.
These bikes are expensive. No dealer can afford to have a Rocket sitting in it's showroom and not selling due to it's colour.
They don't sell in big numbers. In contrast, I would say generally, Royal Enfields do sell in much higher numbers, and then the elephant in the room is, 'how can we sell an old fashioned, low powered bike, that can't compete with modern mid-range bikes in most aspects?'.......I know, let's paint them up in some fancy/cool colours that's on trend this year.
It's a numbers thing.
Marketing has concluded that a Rocket buyer is an egotistical petrolhead type, who is more concerned about big tyres and big torque rather than buying on their sophisticated tastes in colour. Red and Black hit the sweet spot with most stereotypical target buyers......so..... that's wot-we-got-whether-we-like-it-or-not.
They could decide to make buying a Rocket an order only, bespoke bike and in the process an even more expensive bike. Enabling the customer to spec their bikes in a number of personalised ways, which colour would definitely be one option on the list.
I think I would prefer to pay a lower price for the bike and then perhaps pay some extra to make it my own using local paint specialists. Very few of us will keep our bikes stock for long anyway, regardless of paint colour.
I also suggest that if anyone is up for painting their bike in their favourite colour, it will statistically be worth less than the factory Red, Black, Grey coloured bikes, not solely because it's been re-painted, but because it isn't in the statistically preferred Red, Black or Grey. It just works that way with colour....It's subjective, and doesn't add horsepower.......Well ok, Red adds more power than other colours. That goes without saying.......

By the way.......Is Chrome a colour?..........Answers on a postcard to..............