Custard, I'm not saying there is no harm. It is just very difficult to create laws on the basis of sentimental attachment, the politeness of the squatter, or the attractiveness of the property. As a consequence most people who will be impacted by making squatting illegal are people who have nowhere to live or who have insecure housing options.
The situation you are suggesting is pretty much the law as it stands. If you are an occupier of a property or you have evidence that your move into the property was due immediately, the squatter is effectively making you homeless and is commiting a criminal offence.
If nobody is due to occupy the property and you want them removed, this requires a civil court case as it is primarily a financial matter.
If nobody wants the property back immediately, then nothing happens.
If a squatter damages a property they are committing an offence. The fact that the police have not gone and arrested people like this is part of an issue of police not dealing with crime. It doesn't require a change in the law that will put vulnerable people at risk; it simply requires the police to enforce existing laws.
I think people should make judgements about housing based on research into housing and the law, rather than on a tv programme that highlights a very uncommon way of occupying a property that is not yours.