Happens all the time. Lots of people in apartments/houses who don't want an RJ45 running through the hallway nor do they want to pay for RJ45 wiring (particularly when renting).
Interestingly, in the last 10 years I've not met anyone who bothers with RJ45 in the home. Everyone in the UK gets a free wifi router with their broadband, and tends to just use that.
Not saying you are wrong, just different areas are different.
My parents live in a 200-year-old house with Cat6 ethernet in the walls. They needed to replace the electrical wiring, and decided to get it installed at the same time. I don't think they've regretted it, especially as thick walls attenuate the wifi signal. I'm pretty sure this is unusual, though.
More broadly, I think home desktops are getting rarer in the UK. Wifi is the obvious answer for portable devices with wifi capabilities built in, even in dense housing with lots of devices interfering with each other.
That definitely is unusual, but when you're doing a whole-house electric refurb (given what little you mention, it sounds like a tube-and-knob switchout, right?), you likely have everything torn up to hell and back, so you might as well fix or add anything else behind the walls while you can.
People do. One of my friends asked for a "USB to USB" cable last week. (you have how many phones but no USB cables?) Turns out that he wanted to connect the USB type A port on a WD My Cloud (NAS?) directly to his desktop, because connecting the drive via ethernet to the router and transferring over wifi from his basement desktop estimated that it would take 2 weeks.
I would say the vast majority of people use wifi for desktop. (Not myself personally except on the third floor of my house). You might be surprised by the percentages.
also don't underestimate the power of stealing your neighbor's internet. I have a fun little router that's named "dontstealmyinternet". I kept the router's default passwords but have it blocked. It gets about 5 attempts a month from new machines.
My < 6 month old, $4500 USD desktop has 2 x 1 GbE plus 10/100 BMC, but I put an Intel 7265 PCIe card in it and use that instead.
I do use one of the Ethernet ports but it just goes to another router next to my desk (connected via crappy Powerline to the rest of my network) for testing w/ KVM.
Consumer machines have WiFi pretty standard now, my desktop has WiFi. It came that way from the manufacturer. Not everyone wants to rewire their house to where they want their computer.