Instead of having lots of relatively weak core guard posts, why not have just 3-4 per homeworld? You could make them significantly more powerful without actually increasing the challenge of AI HWs and making the assault feel more like a boss battle with the boss going through 3-4 distinct and very interesting stages. You could then remove the boring regular shooting ones and keep (and add) the crazies. Cockroach Post, Zombie Post, Huge-Fast-AOE-Lightning Post, Sniper Post, Dock Post (spawning a Golem/Spiracraft/HK at 75/50/25 HP thresholds) all sound much better when theres only a few of them and you can really focus on them one by one.
Right now the assault on HW is rather crazy since you are in range of several Posts, Raids are coming in and the pressure from Mark V ships is on you. This leads to trying to Alpha Strike the HW and just hoping you have superior fire power instead of a more tactical approach that a few strong posts would force.