I can see where everyone is coming from and have quite often seen this kind of 'vandalism' and yes it is discusting and ruins many a perfect scene. At least if wild camping was legalised and licenced in some manner illegal wild campers who do cause damage/ leave litter could then be more heavily prosecuted. Like I said it would still have to be left at the descession of the local land owner/ forestry commision warden. This kind of system would thus only allow campers if the person 'in charge' of the land belived them to be responsile. Idiots who start fires due to lack of knowledge/ carlessness, leave litter and damage woodland are going to do so regardless of the law. At least this system would allow those of us who have a respect for nature and it wonders to more fully enjoy it.
But like I say this is just my opinion, I fully understand where you all coming from.