Being attractive is not important, but attractiveness is important.
I know, I know, I'm full of it. I'll try to explain.
Attractiveness means both good-looking and bad-looking and everything in-between. It strongly influences how other characaters treat the character with attractiveness. The more shallow the other chatacters, the stronger their reactions will be. The three protagonists from my three stories each have differing degrees of attractiveness.
Alien Fiction The main character is Candide, a perfect human specimen. His attractiveness is important in that story because some of the humor is derived from it. He's a pretty dummy, and the aliens are quick to over-estimate him.
Alien Fiction: The Queen in Yellow The star of this story is Isis, an alien who can take any physical form she likes and chooses to be a small bunny. Her attractiveness is important only in that it's important to herself. She's very vain.
Soulless Saint The main character is 402, a robot. He's unattractive even by the standards of the other robots. He's small. He's dirty green. Some of his joints and pistons are visible through gaps in his armor. This has basically no baring on the story at all.