I t's bad. Ugly appearance, poor system design, negative functionality. It's bad for users, bad for operating system designers, bad for the PC itself. Ugly, dysfunctional, an impediment to progress, a relic of the past, wrong, it has to go.
Some people turn their PC off to save on the electricity bill.
The internal electronics of the machine pull about the same current as a 100-watt light bulb. That one doesn't even deserve an answer. So it should not be there, not even hidden on the back panel, not even as an emergency cut-off switch. There are far better protection measures than depending on the user to see smoke coming out. Let's see what would happen if a PC did not have any such component.