My theory of why Apple added this annoying any-key-or-trackpad-power-on feature is that when they introduced the Force Touch Trackpad with no moving parts and just a haptic tap to make it feel like a traditional click, they thought it was annoying when the machine was powered off that the trackpad didn't click when pressed, which gave away it wasn't a "normal" trackpad.
So they probably thought "I know, why don't we make the trackpad click even when powered off, and while we're at it make the machine power on when the trackpad is "clicked", and oh we might as well make any key do the same thing while we're at it".
I can kind of understand the "cosmetic" desire for the trackpad to "click" when powered off, albeit only a cosmetic thing because who really cares (apart from Apple of course) if the trackpad stops clicking when powered off, but they didn't really need to make it power the machine on too. One step too far methinks.
They should at least provide a setting to disable it based on personal preference, just like they finally did for the power-on-chime which I always found annoying when powering on my Mac in quiet locations like libraries etc. Come on Apple
So they probably thought "I know, why don't we make the trackpad click even when powered off, and while we're at it make the machine power on when the trackpad is "clicked", and oh we might as well make any key do the same thing while we're at it".
I can kind of understand the "cosmetic" desire for the trackpad to "click" when powered off, albeit only a cosmetic thing because who really cares (apart from Apple of course) if the trackpad stops clicking when powered off, but they didn't really need to make it power the machine on too. One step too far methinks.
They should at least provide a setting to disable it based on personal preference, just like they finally did for the power-on-chime which I always found annoying when powering on my Mac in quiet locations like libraries etc. Come on Apple