WordLens blew me away when it launched in 2010 (now part of Google Translate).
https://en.wikipedia.org/wiki/Word_Lens
Had google glass not stored video and processed everything in real-time it could have avoided the "glasshole" stigma.
People would have likely mocked it for not being able to capture video, something they could have added in later in "response to demand".
The world doesn't need more omni-present recording devices, but solid AR would be a net benefit.
Hopefully ARKit/ARCore will make it easier to create the next the-future-is-now level of awe-inspiration app.