The problem is running it 24x7, then a small 50w is still 438 Kwh each year. That's more than a 10% increase in yearly use for a typical two person household...
Now it's up to the person to decide whether increase in living cost is worth it, which... is kinda normal. I think I spend more money on other things that I take enjoyment from.
Maybe having single bulky, but efficient server means other laptops/whatnot will be used less which will cancel out and be electricity negative at the end of the year.