They left out the Krait's no chrome for those wonder why?
It's hard to say. Krait mk II was released in June 2018 and doesn't have a skin. I believe it was/ is the most popular ship in the game according to Arf on the Elite or Frontier live stream maybe 1-2 years ago. Krait Phantom and the Mamba were both released about 6 months later. Mamba is the only one of these that has a Chrome paint job so it's not about release date.
There are 41 "regular" ships in the game (excluding the announced Cobra mk5), 6 ship launched fighters, 2 models of SRV and 3 (cosmetic) variations of fleet carriers. Of these, 31 "regular" ships has Chrome available today.
I hope that with time, and if the Chrome and Gold PJs become real popular, the rest of the models will also have Chrome and Gold. I would so much love to have a Gold fleet carrier. Even if it might look (reflected) black from most angels, when the angle is right, it could be awesome.
Of the newest ships, I think the Python mk 2 and the Mandalay would look great in these PJs but the Cobra mk 5 might be the best suited of all the ships in the game for some mirror treatment. I can already imagine the Buurpit videos featuring this.