I honestly think so, but attractive isn't necessarily over sexualised. Since Kratos was given as an example I am going to follow up on that. If we had a scrawny guy with a high voice play the role of Kratos the game would hit very different.
Character design is very important and since we easier relate to either cool or attractive characters, I would say character design is an important part of the game. Its definitely important for sales, since most people don't want to play as dull looking characters.
Astro is also designed really well and the character design is a part of its charm.
Please excuse my (probally) poor grammar