What is wrong with staying open till 4am?
Most European countries adopt this and it has shown to work, because it allows drinkers to take their time, and they disperse out of bars, clubs and restaurants at different times.
Having one cut off time, makes people rush drinking, and it's recipe for disaster when you let out so many drunk people at the same time.
Then there's the obvious financial benefits to owners of establishments if they want to stay open till 4am. Let's face it most are doing it now anyways.