This suggestion is going to go over a complete rework to the aggression system of the piglins that are going to be added in the 1.16 update (before they are even added). I will also try to include a new "grudge" system to determine how aggressive piglins are to the player and for how long.
The grudge system, put simply, is a system for piglins determining how and for how long they will be aggressive to you depending on how much you pissed them off via thievery and how many times you have killed them.
You will start off with 0 grudge counters, if you don't attack them and don't barter with them at all. I think that piglins should by default be completely neutral to the player character, only attacking them if provoked. If you do manage to annoy them in some way, (attacking them, stealing from them, exc.) your counter will move from 0 to 1. This will give you a grudge potion effect that will last 30 minutes, and make it so if you walk within 5 blocks of a piglin, it will automatically become aggressive to you. This won't trigger any other piglin in the area unless you fight back, and if you run away it will be very fast to forget you ever existence and go back to poking the netherrack with it's sword or whatever piglins do for fun. If you do fight back, your counter won't go up, but every piglin in the area will become hostile and try to chase you down.
When you're counter is above 0 piglins will refuse to barter with you. Should you kill a piglin, or steal from a piglin, your counter will then be increased by one until it reaches a maximum of 20.(this number is inflated as it is fairly easy to find your self in a situation where fighting your way out of danger is the only foreseeable option) killing any sort of elite variation of the piglin, ( not that any have been announced yet, but an example would be the pyromancer mob I suggested a few days ago here https://www.minecraftforum.net/forums/minecraft-java-edition/suggestions/2998048-1-16-mob-suggestion-pyromancer ) your counter will increase by 3.
Increasing your grudge counter will result in a gradually increasing level of aggressiveness from the piglins. From a grudge level of 1-10, the radius in which piglins will attack you will be f(x)=1.5x+5, with x being your current grudge counter. From 11-19 the same rule will apply, with the radius will increase by f(x)=x+10. (Ex: at 5 grudge you will have a 12.5 block radius; 10 grudge is 20 radius; 11 grudge is 21 radius. This decrease in radius gain will nerf the ridiculous detection range piglins could gain for killing too many of them.) A piglin will not under become aggressive to the player if it cannot see them. After your grudge reaches 11, piglins all piglins in the area will attack you if you agro one of them, and it will take much longer for them to stop chasing you after you agro them.
At 20 grudge, an event very similar to the raid will occur. Your grudge will not change until the event ends, but will be set to 10 afterwards. When the event starts, a bar identical to the raid meter will appear at the top of your screen will the title "piglin army", or something along those lines. A group of of about 30-35 piglins of varying types will spawn close to the player's location and immediately be aggroed to the player character and make their way to the player. To end the event, the player must kill every enemy in the army ( to help the player track down any piglins that have spawned in any unusual places, the remaining piglins will be highlighted if only 5 are remaining or the event has lasted over 10 minutes.) If the player dies, the event also ends and their grudge is set to 10.
That's about it. Thanks for reading this excruciatingly long post. I'd appreciate to hear any thoughts or criticism to any of the ideas I made.