Some chatbots let users enter natural-language questions. Others only let them enter predefined choices using buttons or menu items. Both approaches have advantages in the right situation.
The advantages of buttons
Button-based chatbots are far simpler to program, so they cost less and don't take as much time to set up. No artificial intelligence is necessary. There's no ambiguity. Even the best natural-language chatbot often has to say "I don't understand," but that's never an issue when the user has a fixed set of choices.
The buttons show users all the choices that are available. If they don't know that an option exists, they might not ask a natural-language bot the right questions to find out.
Updates are easy. It's only necessary to add a selection to the list and a response to give when the user clicks on it. Expanding the repertoire of an AI-based bot requires more work and testing.
The advantages of A.I.
Making users navigate through buttons works well when there are relatively few choices. As the number of information items grows, it becomes an unwieldy approach. Users will have to enter several responses before getting the answer they need. Navigating through a tree of choices takes longer than getting the information by asking a question.
A well-crafted natural-language bot provides a more satisfying user experience. Getting an answer to a question, without any complications, leaves the user impressed with the system's capabilities.
The welcoming message from the chatbot is important. It should make it clear what kind of questions the bot can answer. It will help users to avoid the frustration of asking questions outside its domain.
When there's a lot of information to provide and a user-friendly experience is important, an A.I. based chatbot can be worth the extra commitment. A badly designed one, though, is worse than a well-designed system that uses buttons.