Part of me agrees with this. But part of me wonders. Let me explain further.If indeed the Hobbit bursts the fourth wall of cinema, and has multiple moments of thousand-foot drops with no consequences for the characters (and major villains uttering cheesy one-liners before they die) then the entire film is spoiled. Why? Because the secondary world will fail to be believable.
The concept of a believable secondary world is something that Tolkien discusses at length in his classic essay 'On Fairy-stories'. In particular, he uses the analogy of a 'Green Sun,' stating "To make a Secondary World inside which the green sun will be credible, commanding Secondary Belief, will probably require labour and thought, and will certainly demand a special skill, a kind of elvish craft." This is (as I have said before) a perceptive a definition of what makes a work of fantasy successful.
In their astute Introduction to their expanded edition of Tolkien On Fairy-stories, Verlyn Flieger and Doug Anderson talk at length at how the essay came at the midpoint of Tolkien’s creative life, and describe how he applied the lessons that he learned in writing the essay to improve his craft, particularly as seen in the advances from The Hobbit to The Lord of the Rings. As they say, “All of these improvements can be subsumed under the heading of the most potent phrase in Tolkien’s essay, “the inner consistency of reality”. The Lord of the Rings has it; The Hobbit has it intermittently, but not consistently.”
So one might think that this lack of an inner consistent reality, a less credible green sun, as it were, is a failing of The Hobbit book that perhaps could be improved upon in a cinematic adaptation, particularly by someone who has already adapted the more "advanced" Lord of the Rings. However, as many of us know, Tolkien himself tried to rewrite The Hobbit to be more consistent with LOTR in 1960, only to give up the effort, reputedly because a friend whose opinion he respected said to him "This is great, but it's not The Hobbit." Moreover, there seems to be a consensus (or at least a majority opinion) among those who have read the 1960 draft in John Rateliff's The History of The Hobbit, that agrees with that opinion.
So my first question is whether in some odd way that lack of a inner consistent reality, that less credible green sun, if you will, is somehow part of what makes The Hobbit The Hobbit. And if so, should not a successful adaptation of The Hobbit managed to maintain that quirky quality? My final question cannot be answered until we have seen the film(s): it is, of course, whether the film(s) have at all succeeded in achieving that, while still maintaining an adherence to the other qualities that make the Hobbit great, its depth, its exploration of different forms of heroism, of the clash of cultures and values, and moral ambiguity, and of course its quintessentially British, whimsical humour.