That was my first reaction, and I'm really surprised to hear that it's not a main argument in the debate.

The first thing I asked when looking at each of the examples in this poll was "Could you sell it without being on dicey legal ground?" If you can, it's probably not a "transformative work" of the kind that needs the OTW's protection. (There are some obvious exceptions, such as fic for series whose copyright has expired, but you get the general idea.)