Some houses we "grew" up with had phone sockets in every room, the modern equivalent would be an Ethernet socket.
And we should also work towards making that a standard, too (i.e. like wall sockets are standard for power, Ethernet sockets should be for data). I'd agree with the notion that "smart" (I'd prefer to say home automation) devices are the way to go, but highly disagree with everyone "Oh just key-in your Wi-Fi password, and good to go!".
Air is a shared medium with inherent collision problems. Avoid it at costs that slightly exceed convenience.
EDIT: Also, home automation. In most people's lives, one's "home" is one of the most static things in life. If anything, your home would be worth spending an additional thought or two on proper planning, to avoid headaches that'll haunt you later.
I know just about everyone in my circle, in tech, filled the walls with smurf tube when finishing basements and any other wall they could get away with.
Not in the houses I've been looking at. Out of dozens I looked sty built within the last 10 years, only 1-2 had it. And the current owners weren't using it.
AFAICT, They're built with the presumption of wifi.
That's weird. It's not expensive to wire houses, and you can't get gigabit fibre speeds with ethernet. You certainly couldn't get anywhere near it 5-10 years ago, but gigabit fibre was available then.
You can use "fish tape" to run wires in walls, mostly non-destructively. Many fish tapes glow in the dark so you can drill 2 small holes, do what you need to do, spackle, and paint.
You probably still wouldn't do any of this in an apartment of course, but I figured I'd throw out the pro tip.
Vertically, sure, but not really horizontally. Aside from just going through a wall, I'd expect most ethernet runs to be more horizontal than vertical, since you're often running it between rooms?
If you have forced air heat or central air conditioning, you probably have a reasonably direct route from your basement/attic to any given room. Just use plenum rated cable, and it's generally pretty straightforward.
Cutting in the box and making up either end of the cable generally takes longer than running the drop.
I've had the exact opposite where devices that could easily have had Ethernet (i.e. enough space on the device) were Wi-Fi only >:(
For stationary devices, Ethernet seems perfectly fine to me. Why force me to use Wi-Fi?