These rules are designed to protect the public - both in terms of direct physical harm and also from the perceived threat of intrusion of privacy.
I really don't see where the grey areas and need for interpretation comes into it. You should not fly in built up areas - even in green spaces and you should keep away from people and isolated buildings when flying in rural areas. People are trying to suggest loopholes and grey areas so that they can continue to fly unlawfully, but eventually this will come back to bite them.
I do totally understand that just filming fields is boring and objects and people much more interesting and challenging, but a line has to be drawn somewhere. We are not flying toys, but serious recreational aircraft and the CAA is keen to remind us about our responsibilities. I would draw parallels with the problems around unlicensed and kids motor cycles and mini-quads. So often these are bought by people with no land to use them on, leading to illegal use on private land and even public parks. Don't buy a quadcopter unless you have access to a suitable flying area.
Sorry, I know it sounds harsh, but I really am concerned that the illegal actions of a few could wreck it for the many. The guy that flies over UK football stadia and fun fairs gets amazing shots and huge YouTube numbers, but he is putting people at risk and eventually someone will get seriously hurt.
For all of this, I would like to see a "park flyer" category for mini-quads under 300g and fitted with a basic camera that cannot be operated from the ground. These are to all intents and purposes toys and should be allowed to be flown in back gardens and parklands, as the risk of harm is so much lower.