For years, Ethernet cables were the best way to get the best connection, and while that's largely still the case, the gap between them and Wi-Fi has closed significantly. In fact, the gap has closed so much that I hardly use an Ethernet cable anymore. My office PC needs one since it doesn't have a Wi-Fi card, but that's the only thing I use a cable for.
Wi-Fi is more than enough today
You really don't need Ethernet for everything
Back when internet speeds were slower and less available than they are today, I understood using an Ethernet cable with everything. I couldn't imagine using my PS4 without one a decade ago, but it's not as important now. I don't have drops or interruptions, and ever since upgrading to fiber internet, I don't have to unplug my router every few days because of a dead connection. Everything has worked fine without a hitch, and I understand a lot of that is because of the reliability of fiber, and I might not feel the same way about Wi-Fi if I didn't move to a place that offered this upgrade. As you can see from the image above, I don't have to worry about speeds at all as I'm able to get 400 Mbps up and down over Wi-Fi.
Ethernet cables are still useful for stability when needed. Buffering hasn't been a personal problem of mine for years, but if you're running into issues like that, an Ethernet cable would put that to rest. Gaming latency is the big one, and if you're looking to play something competitively, a cable is handy there too. On the other hand, I have a PC running strictly off Wi-Fi that I play World of Warcraft on, so it's not like it's a necessity if you can't swing it. Sure, it's better to be plugged in while playing an online game like that, but it's not impossible to play over Wi-Fi.
With advancements like Wi-Fi 6, and now Wi-Fi 7, speeds and stability are at an all-time high. If you have a decent router, I don't think you'll have many issues. I can still get a near-perfect connection on my tablet from my garage, so I don't have many coverage problems. I probably wouldn't recommend playing games out there, but I can easily stream a YouTube video without any slowdowns.
For most people, Wi-Fi is just fine
Ethernet cables are overkill
What it boils down to, like many things, is that the vast majority of people are just fine with Wi-Fi. For example, my parents spend all day using their TV for things like Netflix and Hulu, so there's no real reason for them to be plugged into an Ethernet cable since their Wi-Fi is working just fine. If they were trying to go pro in Call of Duty, then it's a different story entirely.
I'd be willing to bet that most aren't coming close to maxing out their Wi-Fi, unless they are on a low data plan. I specifically chose a cheaper tier for my internet, and I can go much higher than 400 Mbps if I wanted to pay for it. I chose this plan not to save money, although that's nice, but because I knew I wouldn't come close to doing anything that ever needed gigabit speeds.
Many people swear by cables, and if you have the proper hookups, then by all means go for it. If your house allows you to plug in without having to run cables all over the place, it makes a lot of sense. Not everybody is equipped for something like that, and not everybody wants to take on a project to make that happen. I know I don't care enough to get every room hardwired, nor do I see the need to do so.
People value convenience, and that's where Wi-Fi shines the most.
A good rule of thumb is to use an Ethernet cable for anything that doesn't move. This means your TV and computer are prime candidates, but that's only if it makes sense. I'm not running a cable across my house, so plugging in my TV is pretty much out of the question. I'm not doubting your connections are better plugged in versus not, but I'm questioning how much it matters to the average person. For basic streaming purposes, there's really no reason to be plugged into anything.
In some respects, your hand is being forced, and you have to rely on Wi-Fi. I picked up a Chromebook for light internet browsing, and it doesn't even come with an Ethernet port. I'm not all that up to date on the latest laptops, but it was surprising to not even see it included as an option. I don't typically plug in laptops due to the portability, but I don't have the option to do so anymore unless I pick up a USB-C hub with an Ethernet port attached.
It ultimately boils down to personal needs and preferences, and that's why I don't feel the need to stray much further than my Wi-Fi connection. Most people aren't running a server or noticing problems with their streams over Wi-Fi. People value convenience, and that's where Wi-Fi shines the most. I'm not fully onboard with that line of thinking because I still use an Ethernet cable on some things, but I certainly get the appeal of going fully wireless. Wi-Fi continues to evolve, and maybe we'll reach a point years down the road where Ethernet cables are looked back upon fondly instead of being something needed for rock solid connections.