The only source of knowledge is experience
-- Albert Einstein
If I had to give only one piece of advice in this first section of the book on audio for authors, it would be this:
Keep it short, make it sweet, and get it done.
Audio has been around since, I suppose, the spoken language. The difference now is distribution and availability. Audiobooks, podcasts, smart phones, voice controlled home...
It's just so easy. It's probably harder to not do it.
In a nutshell, the answer to Why Now? is because we can. Sure, microphones and book narrators have been around a long time. But...