I'd be happy if interdictions were changed to be balanced rather than favouring the interdictor. That's the biggest problem with it. Of course, including bias depending on your ship's SC manouverability.
That would encourage traders to consider whether its better to make a big haul or a smaller haul in a more agile ship. As i understand it, especially with engineering, a player attacker will win all the time even if you keep on target 100% when flying a more agile ship as long as the interdictor is decent at the game.
If both are on target 100% nobody should be gaining, it should be stalemate. If one loses it, then the other gains.
I'm not sure why this is a difficult concept for FD, and i can only presume that if they did it this way, then NPCs would never be able to interdict anyone, and therefore, since PvE is the vast majority of the game, they feel its better to take the hit on the PvP side instead of the PvE side.
Pragmatically, the attacker should always be at a disadvantage. They can always try to interdict again, and face very little risk for trying. By contrast, the person being interdicted faces great danger every time they're interdicted.
Ideally, the person being interdicted should escape more than half the time, especially from players, even if using a trade ship.