This is literally "why do you need privacy if you have nothing to hide" in other words. What do I think will happen? I think someone at Amazon might be able to listen in on a conversation I have with my wife. I don't want a third party like Amazon to have a recording of things that I say to my wife because it's none of their business and I don't see a big utility trade-off in being able to ask a voice assistant how many quarts are in a gallon in exchange for letting Amazon record me in my private domicile.
And frankly the only reason I carry a mainstream cell phone is because I'm socially required to do so. I don't find the argument of "Google can hear you already through your phone so why not install more microphones in your house" compelling.