I have my own system and I am playing in a large universe. I like to explore the universe but the pirate raids happen too often that I don't get to go too far out before they start bothering my system with raids if I leave it alone.
Pirates raid too much.
The worst part of pirates is not defending my worlds, but the core worlds controlled by every NPC faction aside from pirates. It is the core worlds that (-3/-50%) pirates raid over and over again. Core worlds lack the defenses to defend against pirates, and pirates usually succeed at raiding the core worlds if player does not defend them, slashing their stability. After they raid successfully too much, some of the core worlds will decivilize. Most of my playtime is chasing pirates to defend the core worlds, then grinding rep to fix the constant penalties from factions' expeditions.
Ultimately, I get sick of them and want to destroy all of the core worlds to eliminate the babysitting, although I want to befriend pirates before then.
I don't have problem with defending, but the -stabiility and -accessibility is what i want to prevent without needing to go destroy the base every 3 months or so.
For what it is worth, if all of the core worlds are dead, you effectively cannot get rid of activity because a new pirate base will respawn the day after and put it back on your colony. You will need to live with permanent pirate activity after core is dead. The best the player can do is be friendly with pirates, which eliminate the raids (but not the activity).
With all core worlds alive, they usually pick on a core world, although you still get the occasional -1/10% base that pops up out of nowhere, or the rare -3/-50% when the quota pirates decide to target you instead of a core world.