Hey, why the hate on Days! It's honestly one of my favorites...

Also, Vanitas looking like Sora is definitely NOT a coincidence.Spoilers! Nomura says that before Ventus made contact with Sora's heart, Vanitas had no face at all - kinda like Xion. And since Vanitas' heart is connected to Ventus', it only makes sense for him to take on the shape of Sora. Also, the relationships between the hearts of Sora, Ventus (and possibly Vanitas) may just as well influence their looks, which would explain why Sora still looks like Roxas/Ventus, with a different haircut and slightly darker hair color.