I AM THE LAW
The police generally play quite a small role in the narrative of most Grand Theft Auto games. With the exception of the occasional dirty cop or the scripted appearances of the fuzz you can conduct your criminal activities relatively undisturbed by the boys in blue. Provided you don't run too many people over on the way back from your drug run/gang shootout/assassination mission they'll keep out of the way.
In GTA V we'd like to see the police play a bigger part, in fact, we want to be able to play a cop trying to hunt down the new hotshot law breaker. We're not saying Rockstar should have players hop over the fence completely, instead we want to see two different perspectives on the same story.
A cat and mouse chase style setup would allow Rockstar to explore both the workings of the criminal element in city as well as the institutions in place to trying to catch it. Naturally both constructs would likely be wrought with liars, backstabbers and other colorful characters, so it could be the perfect chance to tell a more complex story.