Hollywood is racist, sexist and abelist and relies heavily on stereotypes. For that is a sad and sorry part of being a human being.
Look at pirate movies, the "good" pirates that are supposed to be dashing lovable rogues usually have all their limbs still attached while the "bad" pirates are usually missing at least one limb or an eye and are uglier.
They also make characters in books that were supposed to be homely-looking more pleasant to look at in their movie adaptations. Just look at Severus Snape in the Harry Potter movies. In the book he was described as having greasy hair and "A face only a mother could love", which meant he was ugly. But Hollywood doesn't normally hire people who aren't superficially good-looking.
Also a person who is supposed to be ugly or obese in media would usually just be average-looking or maybe only slightly overweight in real life. Like I said before, Hollywood is a teensy bit reluctant to hire people who aren't thin or good-looking.