The case was revived because Yorkshire have set up one of those 'Cold Case' police depts that look at old unsolved crimes to re-evaluate whether there is a case against anyone.That's why it's happened now.
As for a waste of police resources I think anything that actually gets someone prosecuted for a crime is hardly a waste of those resources.
Or are you suggesting that wasting and misdirecting police activities in a serious crime is not a crime or not worthy of punishment?