I don't like the cigars in the punchbowl either, but I do agree that Susan's sudden immense popularity is partly due to the contrast between (visual) image and vocal excellence-plus-stage presence.   I do hope that she neither finds fame/success limited to '15 minutes' nor feels she has to have some "extreme makeover (complete with lipo, dental caps, etc.) to be a star.
There was a time when some of our biggest stars, both male and female, were not "lookers." Ella Fitzgerald (who was initially told she'd never make it because she was "too fat and too ugly"), Kate Smith, Mama Cass Eliott, Janis Joplin, etc., were accepted for their talent. TV tended to change that, for women especially.   (The men, it seems, when built like Meatloaf or Luther Vandross or as ugly as Steven Tyler or Mick Jagger are still accepted as presentable on video, while the two plus-size women who sang "It's Raining Men" found themselves replaced by the studio in their own video by much slimmer and more glamorous looking women. And nobody seemed to hold Pavarotti's weight against him as an operatic leading man.

Still, if Susan wanted to do either commercial Gospel or musical theatre, I'm not sure her appearance would have to be a big hurdle. Not all major roles in musicals call for a young, glamourous actor/singer, and Gospel music does seem to embrace many an "average-looking" or not-so-svelte singer.   I think Susan's got a great chance of launching a notable career from this exposure. (Especially if Simon Cowell's in her corner.)