For example, let's say you're planning to approach your boss about receiving a raise, the contents of your speech will be driven by a personal theory of mind regarding how your boss perceives you, your own memory of who you are and how you like to be perceived, the cadence and tenor of speech you imagine your boss is receptive to, information contextually relevant to the purpose of the speech like your proven history of success within the organization, as well as a hundred other variables driven by physiological factors, culture, social habituation and more.
"Predict the next word" just doesn't describe intelligent speech in any meaningful way.