While this is true, at least you control when Siri is listening. You don't control when Google is listening. It's potentially a virtual treasure trove for the NSA and other government agencies.
It's my understanding the moto x only listens when you wake it up with the command phrase but I haven't looked into it much. If it was listening and sending that info all the time it would kill the battery and your data plan so highly doubt it's doing this randomly.