So you can have object look different (by the means of a palette swap) depending on which screen they are and could use more than 6 colors for game object sprites. Or do stuff like changing player palette so that when he goes to a wintery screen it looks like he wears a coat (again, via simple palette swap).
Basically so monsters/objects could use all 4 palettes where monster palettes would be settable by the screen, just like background palettes. This would allow for a greater flexibility and those who would want still use NM as they are now could just set first two (or last two, not sure how it's arranged) sprite palettes to constant thorough the game (on each screen).
Basically so monsters/objects could use all 4 palettes where monster palettes would be settable by the screen, just like background palettes. This would allow for a greater flexibility and those who would want still use NM as they are now could just set first two (or last two, not sure how it's arranged) sprite palettes to constant thorough the game (on each screen).