Constraints help because they favor harmony. If you reuse the same limited palette for all your sprites it's more likely all objects will seem like they share t

Constraints help because they favor harmony. If you reuse the same limited palette for all your sprites it's more likely all objects will seem like they share the same lighting. It's very similar to making music. You can create sounds on a full spectrum of of frequencies but we have constraints like tonality to limit our pitches to semitones and center our compositions around keys. Sometimes we actually want to create feelings of dissonance and then stepping out of these limitations while adhering to them otherwise helps contrasting them even more. Contrast seems to be also one of those things I see even very experienced pixel artists get wrong, especially in the context of games where visibility can be crucial. There's many games with beautiful spritework but actually playing them is very tiring because all of the sprite work uses the same range of the palette. You want to consider if things are in foreground or background, interactable or not, dangerous or friendly and then limit how much the range of their colors intersect. Creating contrast through hues is more common (, see red hostile vs blue friendly), but differentiation through saturation and value/luminosity is much more effective and readable at a glance while also being more accessible to color blind people by default.