PC power consumption is an important metric for those with backup power systems, especially in countries with infrequent electricity delivery (e.g. South Africa).
If you can afford a 320W CPU in the first place, you can probably afford the batteries to power the thing for a few hours, but it does still add a considerable amount to your backup costs.
fwiw a 320w cpu isn't running at 320w all of the time. if you're powering something off of batteries in a consumer situation, a 240w vs 320w cpu isn't going to move the needle unless you're really running it hard (like a game)
The baseline draw is still much higher than lower spec alternatives, and it means you would need to cater for the high end scenario in your battery estimations if you intend to actually use it during power outages.
I switched from a 5950X + 3080, to a 5700G APU, to finally an M1 MBP + Steam Deck last year for this exact reason. Far cheaper to have a 250wh battery that can handle those two for the ±2h outages every day.
For an ordinary consumer UPS that's not trying to keep the system up for hours but just a few minutes, the peak power consumption probably matters more than the average: a 750VA UPS might simply trip its overcurrent protection if you're unlucky enough to have a power outage coincide with a spike in system load. With a big enough GPU, even a 1000VA unit might not be safe.
And it might be hard to get your system configured to throttle itself quickly enough when the power goes out: having the UPS connected over USB to a userspace application that monitors it and changes Windows power plans in response to going on battery could be too slow to react. It's a similar problem to what gaming laptops face, where they commonly lose more than half of their GPU performance and sometimes a sizeable chunk of CPU performance when not plugged in, because their batteries cannot deliver enough current to handle peak load.
Power delivery is fine where I live, mostly decarbonated, too. So, power draw in and of itself is not an issue for me personally.
The reason I care is that a CPU (or any component) drawing this much power will turn it to a lot of heat. These components don't like actually being hot, so require some kind of contraption to move that heat elsewhere. Which usually means noise. I hate noise.
Also, air conditioning isn't widespread where I live, and since it's an apartment, I need permission from the HOA to set up an external unit (internal units are noisy, so I don't care for them, because I hate noise). So having a space heater grilling my legs in the summer is a pain. I also hate heat.
So, I don't see this as buying a "subpar product". I see it as trying to figure the correct compromise between competing characteristics for a product given my constraints.
Then get a low power processor. There’s no reason power consumption should really come up as a prime selling point in any discussion regarding home usage. Obviously when you do things at scale in a data center it makes sense to talk about.
Your original post was to ask why should anyone care about power draw, to which I provided an answer.
Now you shift goalposts to saying you should only care in data centre contexts, in a thread discussing a desktop processor.
It's okay if power consumption doesn't matter to you, but that doesn't mean it doesn't matter to everyone. That's why it's important to have these metrics in the first place and ideally to try and optimise them.
If you can afford a 320W CPU in the first place, you can probably afford the batteries to power the thing for a few hours, but it does still add a considerable amount to your backup costs.