If the "knockoffs" can't capture it, why does it need protection? The logic doesn't work there. You could just as easily defend the cynical interpretation that Teller is looking to "defend" (via the monopoly status of his tricks) his quite substantial revenue stream. That doesn't seem so deserving of protection to me.
The argument (which I'm by no means seeking to make) would presumably be that knockoffs don't necessarily have to capture the same spirit as the original in order to devalue the original — and, indeed, the very fact that they don't capture the spirit of the original is what makes their devaluing influence most powerful.
I feel there's a parallel with music here. Does hearing a great song croaked out by a hack at a wedding devalue the original? Perhaps. But for society it's worth it overall; so many bands get their start doing other people's material. In fact many musicians are only able to keep making music because of a "day job" in a cover band.
Perhaps magic tricks should have the same thing: an automatic license for "covers", where if you want to perform someone else's trick you pay a standardized, small fee to the original inventor.
