So if you're sneaking into somebody's house to steal their treasures, you should probably not sully the gift of Akatosh by using a shout in pursuit of your ill-gotten gains. Following Arngeir's advice, 'true need' should probably be defined by the task that Akatosh has laid on you in giving you the blessing of the dragon blood: stopping Alduin. Instead, your focus should be on the core tenet of the Way of the Voice, the idea that shouts should only be used in situations of 'true need'. So roleplaying a follower of the Way of the Voice doesn't mean giving up shouts.
If you ask Arngeir about the Way of the Voice, he will explicitly tell you that you need to use shouts - to refrain from using them would be, in Arngeir's eyes, to repudiate the gift that Akatosh has given you.
