The reason there is so much talk for a film that doesn't exists is because the ideas of that non-existent film is presented to us in Rises. Rises is a hodgepodge of ideas that could span about 3 or 4 different movies, and yet they're all presented to us in one 2 hour 45 mins time frame. That is a great deal of why many of us are unsatisfied with the final product and believe it to be a clunky movie and the worst of the series. It's trying to be simultaneously an epic blockbuster, deep character story, a war film, a crime drama, and a thinking mans movie. That's all well and good if the execution is perfect, it's ambitious as hell to try and cram so much into such a short run time (relative to the size of the story), but it's execution dependent. If those elements don't gel together perfectly you're left with a film where the ideas presented start to cancel each other out because they're all jockeying for attention, and as a consequence of that lack of cohesion the other flaws in the film become all the more adamant - plot issues, under developed characters, gaps in logic, weak motives, etc, TDK and Begins both suffer from similar problems as well to varying degrees (all films do really), but because the stories in those two films are far more focused you don't notice the flaws as much.
It's all well and good to say judge the film for what it is, but that's all any of us have done. Most of us who don't like the film as much as others have seen the film multiple times, and I'll hazard a guess it because we were trying to work out what it is about the film that didn't work for us. I'm probably not the only one who's replayed the movie in their head and altered it to follow one of the ideas presented to us, and the reason we do that is because we look at the previous two films and see what it is about them we loved about them. We feel Rises doesn't live up to those movies because there is an absence of what made those movies great. Is it fair to judge this movie based on the past two? Yes and No. I do admit every film should be judge on it's own merit, sequel or not, but in a series that has gone out of it's way to be a thinking mans superhero story to depart from certain aspects in the final chapter to many is unforgivable. Add in repeated elements from Batman Begins and Nolan entire body of film work and you've got yourself a potent mix ready for criticism if it's anything short of well executed.
I'll finish by saying I'm pretty certain those of us 'haters', 'whiners', 'nitpickers', whatever we've been labeled, can appreciate what the movie was trying to accomplish and can admire it's scope and ambition, but all we're doing is calling it as we see it, and we don't see it as good as either films one or two. Frankly, we believe there's a better movie within Rises, maybe even better than TDK, and that Nolan could have produced something far grander. In time we may be able to appreciate Rises to some degree, but we're never going to love it.