Thasmodious; Tolkien does indeed show that bravery and valour are often rewarded but the situations you describe are all based upon the characters trying to AVOID slaying. When they meet the Worgs, they are just trying to escape the Goblins but are cornered, and the same in Moria. Of course there are battles, because it would be a poor story without conflict, but the theme of non-violence is repeated again and again. It might have had something to do with the fact that Tolkien saw all his friends die in 1914-1916; a conflict he fought in. He spent most of his life writing stories that are tinged with a hatred of conflict.
A hatred of the necessity of conflict, but a recognition of the nobility and sacrifice of battle for the cause of "good".
The characters in Tolkien's works fight when there is no choice but they take no joy in it.
Some do, some don't. Boromir relishes battle, as do Legolas and Gimli.
If martial themes were so predominant why does Bilbo not slay Gollum when he is invisible and behind him
One characters act of compassion, or two in this case, does not the entirety of the writing represent. They are singular acts. Both Frodo and Bilbo end their adventures with blood on their hands. And let's not forget that Biblo set out from his hole looking exactly to "kill things and take their stuff". He wanted to adventure in search of treasure. Frodo dreamed of adventure as well, but was thrust into a much more dire situation, obviously.
it is because as Gandalf states, that pity that moved him to stay his hand despite the treachery of Smeagol. I think we all know what would happen in a D&D game; sneak attack for +Xd6 damage!!!
Not necessarily and not because the rule demand it. Sparing Gollum would arise from the RP of the characters. An RPed Bilbo or Frodo would make the same call, it was the personality of the character involved. Most of the other characters involved in the story would have killed Gollum.
I wonder if you have read the books or are basing your comments on the films?
I wonder why you have to take to veiled insults when someone challenges your interpretation? I assure you I've read Tolkien extensively and often, I consider myself a bit of a Tolkien scholar having written extensively about Tolkien in pursuit of a degree in literature, including a lot of thematic examination. The works of Tolkien hold up the heroic ideal. Characters are often distinguished through or because of their great battles and martial deeds. The Fellowship is four extraordinary hobbits and five of the greatest heroes of the age, three of which that are distinguished primarily through their combat prowess (Boromir, Gimli and Legolas).
The story of LotR is not just one in which conflicts exist to move the story along, conflict is at the core. It's the story of the heroes of that conflict, their deeds big and small (and mostly martial) and the nobility of bravery in the face of necessary conflict.
The default assumption in D&D is that the PCs are going up against bad guys as well, through necessary conflict. They are not heroes for grave robbing, they are heroes for protecting villages from marauding orcs, ending undead menaces and the like. You don't have to play that way, of course, you can play the mercenary treasure hunters with few morals if you like, its a fairly open system of play.
I think D&D could do a decent Middle Earth game. Flashy magic is obviously not the norm, which is why I think 4e would be better at it than prior editions, because it is so easy to recolor it or make effects more subtle. Playing up how you magically slow your opponents rather than making a flashy ray out of your ray of frost, for example. Magic items are a big part of Middle Earth and D&D does that well. If that's the game that the group wanted to play, it would work, because the players would accept the limits necessary to make the game happen. One arcane caster in the group, perhaps, no clerics, leaving "healing" to warlords and bards. Or perhaps flavor clerics in a different direction, as healers and make healing word less a magical effect and more like the warlords or require a touch to simulate a hasty herbable concoction. "Ahh, I can barely lift my arm after that mace blow." "Here, chew this, you'll feel better."