I think there are certainly reasons to have your "hands-free conversational interaction" device also be able to show you things.
It seems like the big pitch they're making right now is on communications, but there are loads of reasons why I can imagine it being useful. Most mornings, I ask Alexa about the weather. Usually, the voice response is all I need, but occasionally, there are storms in the forecast, and there's a big difference between "60% chance of thunderstorms" and "here's the radar image".
Traffic is another good example. You want to know that there's a 30 minute delay on your route to work, but it's more important to know where so you can plan your route around it.
Just look at human interactions. We mostly communicate by voice, but that doesn't mean that we attempt to provide every answer as spoken conversation. If I ask my hypothetical assistant what a lemur looks like, he or she would grab an image from Google -- not spend 5 minutes giving me descriptions of dimensions and colors.