Some of it is lack of imagination, but some of it is because many truly visionary examples would largely sound stupid to most of today's audience. Imagine it's 2007 and you're explaining how the smartphone will change society over the next 20 years:

- A photo sharing app will change restaurants, public spaces, and the entire travel industry across the world

- The smartphone will bring about regime change in Egypt, Tunisia, Lebanon, and other countries in ~4 years

- We'll replace taxis and hotels by getting rides and sharing homes with strangers

- Billions of people across the world will never need to own a desktop or laptop

- A short video sharing app will kill TV

- QR codes become relevant

Most of these would be a hard sell at the time.