Davidsone

well as far as i know theres no HSV planned within the aussie/nz modders. some other holdens and fords due soon though

Haha! That is true. I'm surprised that Rockstar didn't realise this and officially create a 'LSPDFR'-like mod to start with. 
But having said that, I don't think people play as a cop necessarily to do 'good stuff'. I think the general public (which includes most of the gamers here) always have an enduring childhood fascination of what cops do; the uniform, the weapons, the authority, the flashy lights of a patrol car, car chases, catching bad guys, etc. And given that the GTA world is the only realistic open-world simulation platform that allows itself to be modified for the gamer to play as a cop; that is, there is no other decent game out there where you can experience the graphic detail of doing cop stuff.
I think the same can almost be said about playing as a paramedic or fireman, or to a similar extent, playing games that simulate being a pilot, flying planes, trains, etc. I think people are more fascinated with what these people do, and GTA is a great platform to modify to experience the fun-side of those jobs. However, those of us which are in emergency services, I used to be a paramedic and now I'm a physician, turns out that only about 20% or less of your job is the glamorised fun, with most of it actually being quite mundane that leaves you filled with an element of cynicism. 
And, I'm not sure I always do 'good stuff' when playing as a cop. Haha! When I'm a cop in GTA it seems to give me more abosolution to abuse the poor citizens of the GTA world, and exact swift justice to those who go against me.