Speaking has always been a big part of being a lawyer. You use your voice to make submissions in the highest courts of the land. Even in client meetings, you are also using your voice to persuade. Hell, when I write my emails, I imagine saying what I am writing to make sure it is in my voice.
So, thinking about how a synthesized voice can be useful is going to be controversial. You might think that a computer's voice is soulless and not interesting enough to hold on its own against a lawyer. However, with advances led by smart assistants like Google Home and Siri, Text to Speech (TTS) is certainly worth exploring.