Every time I read about Google Duplex, there is a sense of uneasiness in me. I just can never put it in words. I am not sure what makes me sceptic about the technology. Is it not a useful technology? Or is it the fact that the technology demoed is just too good, sound too useful to be true? I think it is the later.

Google believes in openly demonstrating the things they are working on, the tech they are building. However, they oversell what the tech can achieve; they drumbeat the most ideal scenario without much thought to its ramifications, its pitfalls.

John Gruber, as always, again puts it perfectly in his post on Google Duplex's latest demo.

I still think the whole thing feels like a demo of a technology (the human-like speech), not a product. Google claimed this week that Duplex currently succeeds 4 out of 5 times at placing a reservation without a human operator’s intervention. That’s a good batting average for a demo, but untenable for a shipping product at Google’s scale. With a 20 percent failure rate, Google would need an army of human operators standing by all day long, to support a feature they don’t make any money from. I’m skeptical that this will ever be a product expanded to wide use, and if it is, it might be years away.

Right now it feels like a feature in search of a product, but they pitched it as an imminent product at I/O because it made for a stunning demo.

Exactly. That completes my thought – it's the tech that Google markets. Tech, not a product, can be marketed and sold is a fallacy that Google, for some reason, continues to believe.