The whole setup is a swarm paradise. Locked into the same sector so you cannot outrun or stay out of range (which would otherwise be a good tactic and completely counter them) and no cover to use against them at all.
In an environment like that, an already very cheap and skill-less weapon system (especially if you put it on a logic clock - you don't need to aim it, you don't even need to click fire, you just turn it on and it will lock itself on target) just got absolutely broken to the point that not using it would be straight-up stupid, putting yourself in a disadvantage against anyone who does have it.
Not to mention that auto-swarms will not only track targets by themselves, but since you don't need to click, you can fire another weapon system the same time your swarms to their thing.
Using advanced armor with defensive piercing effect could greatly decrease swarm missile efficiency while your armor lasts, but thanks to its mass, you would have a lot less blocks available for systems, putting you in a disadvantage on either offense or defense, depending on what you sacrifice. Meaning you either take longer to take out the enemy (and thus lose the time you gained with the extra protection) or you'll have a lot less defense against, say, punch-through cannons that bust through armor (and systems behind it) due to the amount of shields you had to trade off for the advanced armor and defensive piercing.
All in all, swarms rule.