Originally Posted by KRSW

Because Google/Siri aren't capable of being fully run by voice (yet). My Echo lives at my office and has become my de-facto office radio. I find its hands-free capability to be brilliant actually.

As far as it listening to everything, I've not found that to be the case, even keeping an eye on it with Wireshark (packet sniffing).

I still see it as a device which is half-baked for now. I think one of the problems Amazon faced was that they weren't really sure what they had created here, which is why it's had basically a year-long beta test. Now that they see what people are using it for and asking it, they're better able to tune the existing one (and create new ones). Still, the Echo lacks audio outputs, any sort of display, and has a hugely limited command set. Siri/Google are much better in this, BUT they still can't be controlled truly by voice only. If you say Play KKJZ to either of those, it will show you that KKJZ exists and has a website but won't start playing it -- Echo will.