People are already doing most of the work of anthropomorphising LLMs, so OpenAI is just capitalizing on that. Drawing a face on it will make people even more attached to the LLM, they will treat it even more like a person. If they ever get desperate for money they could change the cancel flow to have the cute character plead not to die, and play a cartoony animation of its death when the subscription is canceled. It would stop at least a few users.