As I recall during the trial phase of when IDs were ooRP, it confused a lot of people, as some players had made unlawful characters with Freelancer IFFs, and often would use that to avoid being caught by the opposing side of the law. People weren't sure how they were supposed to handle the situation if they couldn't ID the person there or witness them doing something. That's just one example.
However, I've always preferred it when they didn't exist. It allowed a significant amount of roleplay freedom, and when I encounter some LSF ID'd FL IFF'd snub somewhere doing his/her roleplay undercover, I play along unless it's blatantly obvious. For example, if that pilot was flying an Avenger, with Libguns and a cloak, it'd raise questions as to what a Freelancer is doing with military technology.
The same goes for Wild IDs. In a case with an Eagle, armed with KP1's, countermeasure, etc. Nothing really fancy, no given factors of relation, and the Unknown IFF, I'd play along. BUT. Nomad shield, thruster, munitions, guns - telltale signs of when something is wrong, especially to factions or characters that have encountered those particular object in the past. Things like that give away anyone undercover in a heartbeat.
Currently unable to consistently be present in the Community due to life constraints.