I didn't think nail polish was necessary in the The Sims games, but I was wrong. I like the nails and the nail polish. I've notice the colors don't match anything in the game, but I'm kinda use to ...
For me personally, I wear lighter neutral-pinkish shades that aren't too bright or clear polish (I have actual long nails in RL, not acrylics), but for special occasions I want to have my nail color match the shade of clothing I'm wearing (such as coral/salmon, baby pink/mauve, red/maroon, etc) I'm wearing. I don't want a purple-pink/fuscia color on my nails if I'm wearing something that is a peachy pink for example.