Answer:
I don't know if this is the answer your going for but:
I think tints of the bright colors effect the color pallet because it can change based on your moods, kids had very observant moods, happy;yellow, sad;blue angry;red. now that were older our moods aren't as describable, some of the colors describe our undescribable moods and they just fit.
For a more art related response:
its adds more depth and perspective to the piece of art, you can shade it and have the bright colors pop with a darker color added to it. It can also change the tone of the art work too.
Its smart to have black and white when mixing colors so you can mix it to a lighter shade or to a darker shade.
Explanation:
I honestly have no clue if this will help or not, but i tried my best :)