Taking power consumption into account makes sense when the machine is running on battery power, but all modern processors are power efficient enough for the cost of electricity to be negligible for a tiny desktop computer.
I agree for the most part; the exception would be if I were running the small machine as a server. I know this is outside of most use cases, but if I were buying a machine to have on all the time (Plex, email, whatever), I'd want to at least feel like it's not driving up my electric bill.
This is where idle power matters. I recently replaced a pretty low power atom in my nas with a i3-9100F. The peak power usage is probably a good 2x higher, but the idle power is just a couple watts, so I expect my average power draw to be much less since the power draw under plex/etc is about the same and the machine sits idle most of the time.
Hypothetical scenario: You save 50W (maybe too high, maybe not), use the machine for 10h every day, and a kWh costs you €0.40 (eg in Germany). You save €0.20 per day, €73 per year, and €365 in 5 years. Definitely a factor in areas with high electricity prices.
I think for most power users, they probably generate significantly more than €73 in value from the computer every day (or maybe every hour), so they are probably not thinking too much about that savings.
(Of course, power savings are important in their own right for mobile / battery-operated use cases.)
