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.
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.