First of all, its not 24-hour drinking. Hardly any pubs have 24-hour licenses (Hotels & casinos have the vast majority) and even fewer use them, so the term 24-hour drinking is only used as an emotive headline by scaremongering journalists. Unfortunately the drip-drip-drip constant bombardment has meant that even the BBC uses the phrase.
I'm for extended licensing hours as it ends potential flash points at taxi ranks, restaurants and kebab shops where all the people who are thrown out of pubs at the same time congregate. If pubs close in phases over the period of a few hours then less people need these services at the same time.
Need police help at 23.30? Good luck - they're all dealing with the above flash points. With phased pub throwing out times, the crime aspect at best decreases and at worst is spread out so that the emergency services can better deal with it. Reports that crime between 01.00 and 03.00 has increased should come as no suprise as the crime has been spread out.
It will take a generation or so before we can get a more European drinking culture but if the allotted drinking times are restricted to narrow bands of the day then people will feel the need to rush the beers down their throats before the deadline expires.