The problem with piracy's game design is honestly most visible when you compare piracy missions to liberate missions - it's as though a lot of the time people on the design team forget that illegal options even exist. Smuggling missions still break if they offer a material reward and your store for that material is full.
Liberate - when allied, you're asked to fetch 4-8 tons of a particular, mission-specific commodity. The target is carrying exactly that amount of that commodity, and they also carry a bunch of other cargo that drops afterwards, that you can swipe and sell for some extra gravy if you're so inclined. When you hatchbreak them, the mission cargo drops first. The target is invariably wanted, so you don't get attention from the cops and you can blow them up for the bounty when you're done robbing them of you're so inclined.
Liberate missions are great.
Piracy missions - you're asked to fetch 90-130 tons of some commodity, which rules out all small and most medium ships for the task immediately. The target is not wanted, so you have to deal with the cops if you don't get them in an anarchy system. The target only carries that mission commodity, and if you steal extra then it's still marked as mission cargo so you don't even get to keep the bonus. You can't take them unless you have the cargo space available right now.
I very rarely take piracy missions. It's telling that the legal version of the "find some guy and steal their stuff" mission is worth doing and the illegal one is not.
As for signal sources? Threat 2 convoy signal sources will spawn a military T9 escorted by two condas, or two T9s accompanied by four vultures. If you scan them, they're carrying... a ton each of antiquities, plus some other dross. Jacking that cargo is not worth the time or risk of taking on those escorts. A low-volume high-value heist would be a great scenario, but the value of the stuff they carry isn't actually worth it.
There is one signal source scenario that's actually fun as all hell - namely, the one where half a dozen T7s spawn and then you get the choice of defending the convoy or helping the raid. If you choose to help the raid, you're told to hatchbreak them - the pirates just want to grab 10t of insulating membrane off them, which is fine, but they're also carrying other stuff. The stuff is usually the likes of domestic appliances admittedly, but all of it is pure profit. If the stuff in these convoy heist scenarios was more lucrative (or you got missions to direct you to this scenario) then it'd be amazing, but the extra stuff you can steal seems to be balanced towards the earnings that were available when the game just launched, where a ton of domestic appliances was a fantastic haul (rather like the first fast and the furious movie, where the AMAZING HEIST was for CRT TVs with built-in VCRs)
The big thing about a lot of legal missions is that you get a bonus in the form of bounty payments afterwards, plus usually you get help from authority ships. Piracy missions, and illegal missions in general, you don't get the opportunity for that bonus (if anything, the recent bounty buff has only increased the disparity!) and the cops are a hindrance rather than a help.
That, and honestly - in the time it takes to track down a target for this BIG SCORE of 1 ton of antiquities or whatever and get away under fire from half a dozen navy ships, I could have dropped on literally any metallic ring and safely mined several times that value in gold and platinum, hell even silver.
