Which is a nice game mechanics but from any other POV pretty silly. So, the power-plant is the most required piece of equipment but it's as exposed to fire as is an external system like the thrusters? Not covered by armour? That's nuts. I do like the idea of subsystem targeting as it adds fun buy yeah, some mechanics don't add up sense-wise.
Not only is the power-plant the 'most required' but it is the one that blows your ship when it reaches 0% - no turn it off and on again and repair on this module.
I see no logic in any ship (let alone a multi-purpose or combat ship) exposing it's most important component like this (not a lore/sci-fi explanation, nor in gameplay/mechanic terms).
I do see why you might want to allow targeting of various systems as a player may choose to try and stop another ship from shooting back, repairing shields, running away, dealing with heat, using chaff etc.... That adds gameplay and choice and variety. Everyone targeting power plants does the complete opposite and just seems to make armour types more or less obsolete (especially on larger, less manoeuvrable ships, the ones that need it the most).
If the power-plant were hard to destroy and it gradually provided less or inconsistent power to other components (as it slowly got damaged) it would make more sense (to me) but I have never liked the vulnerability of the power-plant or at least it blowing up the ship regardless of any other component or hull damage.
Not done it to a player, but I have more or less one-shotted an npc Anaconda with 5 gimbal pulse lasers after taking down it's shields while it still had 86% hull. Where is the sport in that?