I agree with the fact that power systems are counter-intuitive in the way they take damage.
If you take damage to a power system, you just loose power generation or storage capability which works for the moment.
But look at it this way. If power cores were in the game. What stops me from just making many many power cores with their own capacitors and generators?
If there is a limit imposed, it would be arbitrary.
If it's expensive to buy or make, then perhaps that would make people think twice, and consider protecting it more, but it's not going to matter to the big players or factions, it will only increase the effort involved in making ships. People can still build as many as they want, and all that has been achieved is a increase/cost in build time.
At the moment, it doesn't work ideally, but it works better than it would do with cores. When power systems start taking damage, you have a reduced power generation and are able to do less, eventually to the point of death. It's attrition based combat, because if it worked like it does in Star Wars, combat would be over almost immediately as the enemy explodes in a ball of fire, and that would be boring, and also frustrating for the you if it were you that suddenly exploded or lost all power.
Currently if you want to be more survivable you build excess power. This is the only strategy currently, which can make certain ships bonkers powerful because power generators currently are dirt cheap to make. So you're on the right track.
So I am all for more complex or vulnerable power systems, but I do not believe a power core block is the solution. You need to flesh out the idea along with it's potential problems.