The only gripe I have about geocaching is when the anonymity makes it possible for people to find a great looking geocoin and then keep it for themselves! Part of the fun of the game is to pass it on and see where else it goes! Now if I found a laminated piece of paper with a picture of the geocoin on it I'd definitely feel swindled! Owning one coin I might be able to understand this, but if the owner has 30 coins all like this they need to physically let some go out into the world to travel.
I understand the owner's apprehension about it getting taken, as I feel the same way with great coins I pass on so I just take pictures to remember them by and then post them on http://thebestgeocoins.tumblr.com/