Jeff C has done an excellent job justifying the existence of Bombadil but only by an academic tour de force. Let's see if I can do as well in my reply to his accusation that I don't know what I'm talking about.

Jeff C attempts to argue that Bombadil ought not to be excised because he serves numerous purposes, not least of which is making the quartet of Shire Hobbits' utter naivete of their wider world become starkly apparent. But surely the experience of Old Man Willow and the Barrow Downs were enough to do this? Was it so necessary to have such a Cosmic Fool of a character as Bombadil to save them? Was Tolkien such a sloppy writer that he needed this character for the 'light and shade'...? Or did he have his heart so set on this happy-go-lucky character that he couldn't bear too NOT have him in the plot...? Or is the real truth that Tolkien didn't really know where he was going when he was writing the early chapters of LOTR?

And if Bombadil has unrecognised profundities (that readers are encouraged to at least acknowledge) why don't the Hobbits drop in and pay him a visit on their way back from Mordor and Gondor? Surely it would be polite at the very least? [It would also be highly appropriate literarily, in that it would tie up a few loose ends]. Wouldn't such an important character as a good Maia (representing all those things the 'good' Maiar are supposed to represent) merit some kind of an 'epilogue' chapter or two at the very least?

Or did Tolkien ultimately recognise the plot limitations of this fey character and wrote him out entirely? In other words, Bombadil 'did his good Maia bit' in those early chapters, but was made to quietly bow off stage ... so as to let the grown ups get on with the business of living, fighting, struggling and dying in the REAL big wide world that Tom won't venture into. Because the LOTR ended up broadening out into a grown ups' world with death and blood and pain... awful lot bigger than Tom's neighbourhood... where grown up decisions have to be made without recourse to local deities like Tom.

Thus, arguments justifying the "plot-worthiness" of Bombadil based on speculations about his cosmic significance founder when one looks at the plot development and protagonists' experiences in the text as a whole. In short, Tolkien and his book LOTR outgrew Bombadil.

The facts are that Tolkien spent the better part of fifteen years or more writing Lord Of The Rings. His attitude to that work itself changed as time went by - and this is reflected in the tone of the work - just compare any chapter from Book I to any chapter from Book III onwards. The Hobbit was written as a fairy tale - an offshoot from Tolkien's own fantasy world, granted - but a child's fairy tale nonetheless. Once Tolkien got into the telling of LOTR the scale and tone of that work dwarfed (no pun intended!) The Hobbit and in some places [especially when non-Hobbit characters speak] is more like the style and tone of The Silmarillion - a earlier work, but one that was reworked again and again and remained unfinished at his death. The Simarillion resonates as an 'adult' work, its characters and the whole mileu echo with archetypal mythologies of the Western World. The latter chapters of LOTR do the same. Indeed, The Silmarillion and LOTR belong as a pair of epic works - the first's style being largely grandiose and studied, the second's mostly warm and human. In this manner they are akin to The Illiad and The Odyssey.

But the irksomeness of Bombadil is not just due to his plot irrelevance.  Even if we decided that Bombadil served some useful purpose as a character, and had some merits as 'background colour', he just doesn't sit well with Twentyfirst Century adult sensibilities. And, no, I'm not trying to sound jaded and all-sophisticated here. I think we are all too aware of world wars, famines, holocausts and political deceits to warmly receive gods that seem to sit beyond our sufferings. Put bluntly, the Maiar, the Valar and even the Elves can turn tail and run to Valinor when the going gets too hot. [Unlike Tolkien himself, and millions of his fans, apparently, this is where I and they part company; I am not enamoured of glistening immortals, fictional or otherwise, whose sufferings arise from their own stupidity]. Mortals don't have the luxury of an out when the going gets tough. We have to put up, or shut up... or die. So when Tolkien stops telling tales about grand Elves and shining awesome sublime Valar - and starts telling stories about real human sacrifice and suffering - his writing achieves its greatest heights and profundities. And in these places, the Bombadil character (despite all his apparent affection for it) becomes grossly indecorous. And so I wonder, surely Tolkien must have realised this himself?

Therefore, in the final analysis I answer my own question as to why Bombadil appears at all; his appearance is nothing more than a bow to the writer's 'pet' icon for all that's nicely, antiquely mysterious about English country life.. and some clumsiness with plotting on Tolkien's part.