I'm sorry for remaining a bit skeptical, perhaps if you could PM me an example of these sorts of beautiful fanfiction.
Anyways, I can see how you can turn that sentence back to reflect your feelings. I can't really state anything new at this point so I won't bother, as I'm sure it'll just get annoying to you, everyone that reads it, and myself
I think creating a new world and new characters gets the point much further across, mainly because you don't have to shape your message by your setting/characters (although plenty of people burst through those walls as if they were cardboard, which can cause a cringe in the staying-IC department).
I'm going to admit that perhaps I just happened to have never stumbled onto good fanfiction, which could be all the cause of the negative feelings towards it. I just feel that, if one would write as fanfic, they should retain as rigid a structure to stay IC. Which is a lot more trouble that it's worth, because your creativity can be greatly limited. Those that go ahead and bend pre-existing characters to whatever they feel like are more or less, in my eyes, actually doing injustice to the original creators. It may seem less important because of how "far away" the original creator seems, but I think it should be taken as seriously as if someone ripped an underdog's original character away and made them all sorts of OOC just to portray some really obsessive, really scary passing fancy.
Fanfiction is indeed a great marketing device. I agree.