Dervish and the rest have already put it quite nicely, but I'm gonna throw a few wordy words down on all this.

I see absolutely nothing wrong with fandom RPs, and I myself participate in fandom and "original" RPs in about equal measure. Cliches (and tropes and whatever else) aren't necessarily bad,and it's much easier to understand something that's based on something else.

So I have what I think is a really cool idea for an original story that I've called //godEngine.INITIALIZE, but unfortunately I've found it very hard to explain in a way that makes sense because it doesn't borrow heavily from any sources (at least consciously) so it's very hard to make the player understand without making them read walls of text that will make little sense to them. On the old guild I ran two fairly successful original RPs (one might be the one that LoneSilverWolf mentioned?), but that also depends on what your definition of original is. To be original does it have to not draw from any sources at all and only come from your head? Because I think that's nigh impossible in this day and age for many of the reasons Dervish stated above. I've found that original RPs work best by mixing things that are familiar to players and throwing in your own twists and original stuff.

So one of these RPs was called "Iveron, of Gunpowder and Steel", it was a fairly original (in my opinion, though the plot wasn't all the original I felt like the world was). It took place in a fantasy world recovering from the aftermath of a large war against the Fae (which were less "Oh, faeries and elves and gnomes, yay!" and more uncanny valley and Lovecraftian horror along with old fairy tale stuff like kidnapping children). A long time ago, humanity (in it's purest form) died out, but before they died they created a sort of immortality drug that had some pretty bad side-effects, including going blind, albinism, and other mutations that made them rather unnerving to most other races. There were Satyrs who lived in nomadic clans, and the (admittedly horribly named) Masque... Who wore masks for unknown reasons (we decided because anybody that saw their faces tended to go insane), we had bird-people with a chess based caste system, we had animal shifters from an island nation off the coast, we had people made of fire/water/stone/whatever-other-element. A mysterious Council that acted as a sort of universal law that governed the use of magic. A lot of that was pretty familiar to fantasy fans, some of it not so much, but we made our own world from it, and it worked (though real life did get in the way)! For pretty much all the original worlds I create, I borrow from other sources and twist things around and add in my own stuff.

As for fandom RPs (even though plenty of other people have said it), I think it's quite possible to do an original RP even if it's set in another world that's already been made. You can build onto the world, have an alternate series of events happening in the world, and plenty of other things.

Uh... I'm not sure what else to say so... Uh... Carry on, I guess. Hopefully that contributed to the discussion.