In the book, didn't she look better when she was younger?
Yes, in the book she was supposed to be a real looker when she was younger. I think the whole bald head and no eyebrows look was just invented by David Lynch to make her look creepier.
On a side note, the later books state that the sisters could have all but stopped aging and kept their good looks for an indefinite amount of time, but it was forbidden. They figured an order of ageless women would worsen their public perception as “witches”.