So clearly I was being a smartass about Padma and Tom and the red slip. But I do think that's one of the main reasons why Padma is there. She looks good.
I'm sure that when the powers-that-be envisioned the show, they elected to follow the standard competition show format: contestants, judges, host. And they began auditions for the host. They may have decided from the beginning that they wanted an attractive, well-spoken woman, or they simply may have narrowed down a wide range of potential hosts to her. I don't know. But her role clearly began as a host/hostess/"presenter" in the manner of other hosts/hostesses/presenters, like Kat Deeley, Ryan Seacrest, Carson Daly, Nick Cannon, etc. She's there to say "Welcome" and "Our guest judge is" and "Your next challenge is" and "Please pack your knives and go."
Most of these competition shows have this same format. Gordon Ramsey is the exception. On his shows, he's the host, judge, jury, executioner, but that doesn't seem to me to be the standard.
How Padma morphed into what appears to be a full-fledged judge, I'm not so sure. But most likely she's there to stay. She's one of the producers. And with the exception of here, there doesn't seem to be a huge public outcry to get rid of her.