From previous discussions on NPC challenge it's common for those asking for more challenge to have a relatively low rank so they are not seeing the maximum challenge the game presents.
tbh I think the interdiction mechanism has historically been plagued with bugs, and has been both too easy and too hard. I'd rather leave it alone, it seems to be very sensitive to change.
While there have been issues in the past, leaving NPC interdictions as they are wouldn't be much different than having a pop-up box that comes up saying "Hello, so-and-so would like to meet you! Do you consent to this interdiction? Yes? No? Are you sure?"
Keeping things as they are doesn't do anything but make them entirely optional and give a false sense of confidence when confronting one's first CMDR interdictions. We've even had threads where players have questioned if someone were likely cheating because they repeatedly failed to escape interdiction, yet had a good success rate against NPCs.
They could gradually increment difficulty for higher ranks and analyze the results if they are worried about going too far, but for now it's as much a placeholder as the auto-interdictions were before they added the tunnel game.