The issue here is that it isn’t unknown. It’s high sec space. This is highly civilised space which displays NPC’s and gate guns on every single gate, sometimes several different squadrons of ships. FOB rats suddenly reinforcing structures and gate camping in this is a massive break in immersion.
If you want this to happen then you need to change the overall feel of highsec before introducing such rats, remove the NPC’s off gates listing ‘Empire patrols are worked to breaking point so have to cut back on gate protection, trusting to the gate guns’. Then have the FOB patrols actually have a shoot out with the gate guns (or move the gate guns onto the gate itself and then have them shoot the gate for a bit to disable them, or both in order as an evolution to reduce cost from lost platforms).
This in no way reduces the unknown, but it does make the unknown logical. A 1% chance of dying every time you jump through a gate is unknown and scary after all. But it’s not interesting or controllable. And that’s important.
(And yes, I know a lot of ships can survive the FOB rats gate camping etc, but it doesn’t change the fact that suddenly we have pirate NPC’s doing things players can’t even dream of doing)