The idea
There is a need for public order offences however there are some demonstrable inconsistencies in them that need to be cleared up.
Section 5 dealing with offensive language and conduct. Most people would assume this law relates to "swearing" however the way the act is written allows a great deal of latitude because it allows for subjectivity. The most common issues are during protests, for instance the threat of a section 5 arrest has been used to prevent protestors in the UK from using the phrase "dangerous cult" with respect to the cult of scientology because it was deemed as possibly offensive to scientologists, whom I doubt would disagree.
Ironically legislation relating to religious hatred (2006) includes the very specific protection for the freedom of expression, which according to my research in Hansards was in part inserted in light of comments related to the church of scientology which states:
"Nothing in this Part shall be read or given effect in a way which prohibits or restricts discussion, criticism or expressions of antipathy, dislike, ridicule, insult or abuse of particular religions or the beliefs or practices of their adherents, or of any other belief system or the beliefs or practices of its adherents, or proselytising or urging adherents of a different religion or belief system to cease practising their religion or belief system."
which means you should be able to say scientology is a dangerous cult.
I can understand the need to protect people from threats or personal abuse but not the need to protect them from being offended especially since it is down to the police to decide whether or not your offence warrants their time and effort.
Why is it important?
The public order offences are out dated and do not take in to account things like freedom of expression. There are many examples of people falling foul of these offences unwittingly by either saying the "wrong thing" or even wearing the wrong thing, notable occassions of people being arrested for wearing an offensive T shirt, particularly anti-blair and anti-bush ones.
It isn't that these cases always get to court, in a few cases I know of the person was arrested spent the night in jail and was then released, presumably because the CPS decided it was frivolous case.