As far as I know, Roberta's one-year contract was coming to the end. A couple of weeks before that she was asked to get a short haircut. And when the time ran out, the contract was not extended, and replacement was introduced. Surprise! She had short haircut. And authors quickly wrote Flame out of the plot. Roscoe Born was just furious about this.
By the way, Flame, like Cassandra, was Conboy's fulfilled promise to introduce more young sexy female characters. In my opinion, the early period of Conboy was not so bad (up to the story of Andre Wolfe and Lisa).