I thought my HomePod had a display all along. OK, it's not a LCD or micro-LED capable of playing videos, it's just an array of LEDs that provide a bit of visual feedback during setup/reset and spoken interaction with Siri. But it begs the statement, "If Apple had meant HomePod to have a display, it would have had a display."
My general feeling about "add an LCD touchscreen to it" - whether "it" is a telephone, refrigerator, a car's dashboard, or (for those with a sense of history) computer is, "To what degree does this enhance usefulness?" Clearly, a video display on a computer is a slam-dunk - anyone who's used a Telex-style TTY loaded with green bar paper as their primary computing interface can tell you that. LCD touchscreens also enable a much wider range of uses and adaptability than a control panel loaded with physical buttons and knobs (automotive dashboards are a prime example). But limited-task devices are less compelling with video/touch interfaces than broad-purpose devices - does a thermostat really need a fully-capable touchscreen video interface when it can remotely piggyback on another human interface device?
That's likely the question asked when HomePod was in development and why it got that array of LEDs instead of a high-resolution LCD touchscreen - visual feedback would be useful, another screen, less than useful.
So where do displays fit into the Smart Home? Somewhere in between. People with expensive homes and large discretionary income have had speakers (and later, screens) in what used to be called "intercom" systems for over a century - every room in the house equipped with a wall-mounted panel that connected residents to the front door, kitchen, etc. There was a natural tendency to tack on additional features - horrible, tinny speakers playing music from expensive Muzak subscriptions, eavesdropping (baby monitoring), "security" cameras, etc. - as technology has evolved, more of these capabilities have become feasible for the wealthy, then upper-middle-class and now the middle-middle-class.
But in a lifestyle where every family member has one or more screens at their immediate disposal (computer, smartphone, tablet, Smart TV, smartwatch, etc.) the need for things like wall-mounted intercom systems has evaporated. Why get up and walk across the room when you're already holding a totally capable communicator in your hands? Why attach something to the wall that's useful a few times a day when you can have something in your pocket that you use constantly? Features like "electronic picture frame" are a joke - an extra selling point rather than something that meets a consumer need. Do you want a display of great artwork or family snapshots on the wall? You wall-mount a Smart TV. Do you want more than one in the room? Computer screensaver!
(And what about a thermostat/temperature sensor in each room? It's only useful when the HVAC system is zoned/controllable for each room. Most homes would require a very expensive retrofit to deliver that - the temperature sensor in a smart speaker is just the tip of the iceberg.)
"Distributed intelligence" is something else. The relative success of smart speakers recognize that many basic needs can be accomplished with a voice command/voice response. It can save you the trouble of pulling your iPhone from your pocket or walking over to the computer. It doesn't mean every smart speaker has to become a fully-functional tablet. Sure, people may find that useful in a few of the smart speakers scattered around the house, but not for each and every one of them.
If Apple is developing a HomePod with camera and video display it's not going to be a replacement for today's audio-only HomePod/HomePod Mini (and AirPods, for that matter) - it'll be one or two additional models.
