Oh, for heaven's sake it's not complicated.
File sharing as a concept CAN be legal. The legality stems from the appropriate OWNERSHIP of that which is being shared.
The courts can rule that P2P is not a problem, only what it is used FOR. IF it is used to distribute property against the wishes of the property owner then it is a medium being used to facilitate theft.....and is identical to the person sitting in the Cinema with his video camera making a 'copy'.
In that case it can be determined that using the video camera in a Cinema for such end is 'illegal'. [simply because you WANT a copy does not make it just, legal, OR right].
It does NOT mean that using a video camera is illegal, or that a camera user is evil or any OTHER such tripe you attempt to ascribe to my comments.
HOW you use it is the problem.
HOW you break a speed-limit in a souped-up car is the problem.
WHAT you do with that 'legally-purchased' gun is the problem.
WHAT you do with that 'legally-purchased' software is the problem.
YOU can break the law by selling a burnt copy of it on a street corner.
YOU can break the law by giving it away freely on a street corner.
YOU can break the law by giving it away freely on P2P.
So what if the courts were/are lamenting the complexities of restricting P2P to legitimate use. Yes, that's hard...how to legislate or control illegal use of something [currently] virtually uncontrollable?
The difficulty isn't moral or ethical it's simply logistical.