I don't want to keep on going on and on about this, but "desire for independence" reads like a red thing to me.
To expand on this, black does not care as much about independence as it does about power. Black has no qualms binding itself to a higher power, like demons, if it means to become more powerful.
I doubt Skysail is really associated with Indatha as much as the planeswalkers guide makes it look. It's a nomadic "everywhere" kinda society after all.
One of Black's main things is individualism. By necessity that implies a craving for independence. Black is willing to submit to higher authority if it can get a reward out of it, but whenever possible it wants to do its own thing. Hard to be powerful if you have to do what someone else wants, after all.
"The natural place to center wedge factions is in the enemy color (for example, white in red-white-black). It's intuitively what everyone assumes, as it's the color that has the same relationship with the other colors. The only reason we didn't do that in Khans of Tarkir was that we couldn't. You see, the factions started as wedge in Khans of Tarkir and then, after time travel shenanigans, turned into ally color factions in Dragons of Tarkir. Creatively, the factions shifted but had the same core identity. That meant we couldn't center it in the enemy color, as that was the one color that disappeared between the first and last set of the block. Originally, by the way, the factions in Dragons of Tarkir were enemy colored, but it turns out that wedge sets and enemy color sets draft similarly, so we had to change it.
When we got to the plane of Ikoria, we were in a new world that didn't have the restrictions of Tarkir, so we let each wedge center itself where it felt most natural, which was the enemy color. I think this is a good thing because I like having mechanical elements that further differentiate the two wedge worlds from one another."
I mean, it does though. Knowing how your colors will pan out def helps with world building bc it'll guide you as to what fits and what won't both with mechanics and flavor. Maro is acknowledging that Tarkir did the alternate take of Wedges first, and now Ikoria gives us the actual depiction of the Wedges, letting us see how the center color influences its enemies. Take Mardu: instead of crazy, ruthless nomads with a loose society, we get a tight-knit society working together for survival. This also helped shape the world with how the creature types got selected for each triome. Snapdax, Apex of the Hunt gets to be a Dino Cat Nightmare, since Red centered Dinos, White Cats, and Black Nightmares, where on Tarkir, they'd just be another dragon.