The icing on the cake was how popular this edition was.
When I heard, later, that the film was going to be a three parter instead, I thought "Uh oh. There's plenty of material for two films, but three? Filler City, here we come."
My wife and I saw the movies in the cinema, and while we enjoyed them overall, I found that I was right about the filler. I was particularly annoyed by the barrels-down-the-river scene, where the film turned what should have been a moment of quiet drama into a sort of rails shooter on the screen. That scene threw me out of my immersion; the whole time, I was thinking "The only reason for this scene to exist is to be made into a video-game level." As a video game level, it would kind of work: you're in the barrels floating downstream, and you have to shoot enough orcs with the bow you somehow have (or flatten them with your barrel that has been inexplicably launched out of the water) to stop them from killing your friends. (Or perhaps the video game level would make more sense if you play as the elf on the shore, killing the orc archers before they can shoot the fish^H^H^H^H dwarves in a barrel).
Regardless of how that scene would work as a video game, the problem with it is that while watching it, I was laughing at how ridiculous it was, instead of on the edge of my seat with excitement. That is NOT what the audience should be experiencing, and it means that someone — director, producer, screenwriter, editor, who knows — made some very poor choices in putting that scene on-screen.
So yes, I'm not at all surprised that a fan edit of The Hobbit which removed all the filler would be wildly popular. In my case, I would rather buy a 4.5 hour version of the film than the officially-released version. If only that version was for sale legally.
P.S. Not all the filler material in the Hobbit film trilogy was bad. Some of the scenes that weren't technically in the original book, such as Gandalf and Galadriel discussing the threat of The Necromancer, were a positive addition and helped link the Hobbit film to the Lord of the Rings trilogy. If Jackson had stopped there it would have been fine. I have never watched the fan-made "Tolkien Edit" recut version of the Hobbit film(s) so I don't know if that scene was included or not — but in my opinion, that one would fit into a "Tolkien Edit" even if it wasn't technically part of the original book.