I guess this would depend on one's definition of "heroic fantasy". IMO, the rules do a fairly good job of creating a game of the type of heroic fantasy found in sword and sorcery tales.
Perhaps you should define exactly what you mean by "heroic fantasy".
Again, please define "heroic" because I'm sorry but I don't get what a "default storyline of heroic conflict" is... the stories I've read are so varied and different I find this kind of artificial when you try to apply some type of default to all heroic fantasy... and in fact I am beginning to suspect that you are moreso speaking to a very narrow band of heroic fantasy when talking about this supposed default.
In some/many/most heroic fantasy dungeon or wilderness journeying, and loot are a big part of the stories.
By "heroic fanatsy" I mean fantasy fiction in which the protagonists are motivated not by mercenary reasons - the desire to kill and loot - but by values - the righting of (perceived) wrongs, honour, justice etc. In the context of D&D, this would be PCs who fight goblins not to rob them, but to proect the world from them.
Here's one example of the conflict between heroic fantasy play and classic D&D play: players who are playing heroic PCs will not ignore wandering monsters, because (presumably) wandering monsters are as dangerous and wicked as placed monsters. This means that, in a heroic fantasy game, wandering monsters will not play the mechanical role they were intended by the game designers to play (as indicated by Gygax in his PHB - he instructs would-be skilled players to avoid wandering monsters because they carry little loot).
But even looking at something more "high fantasy" such as The Hobbit... Bilbo and the Dwarves are pretty much amoral treasure hunters, who explore wilderness and dungeons while slaying and or fleeing from dangerous creatures that are for the most part unrelated to Smaug
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I mean even Arthur's quest for the Holy Grail can arguably be described as being about loot.
The Hobbit is not about amoral treasure hunters, and I'm a little surprised anyone would read it that way. The dwarves' claim to the treasure is based on ancestral heritage, not "finders keepers", and the book ends up as a morality tale, in which the lust for treasure leads to wrongdoing and suffering.
Read the Grail quest as a story about loot is a little odd also. It's a story about redemption.
REH's "The Tower of the Elephant"
is a tale about a protagonist motivated by loot, but even it ends up being a type of morality tale. Classic D&D can't easily produce even this story, because in the end Conan misses out on the treasure - as a D&D character, he would earn no XP for it.
But there are rules for where and how one can gain a magic sword and the stats for dragons... this seems a little specific and more centered on campaign setting creation as opposed to the actual rules. I know for a fact there were published adventures with hermits who had treasure... not sure about an official "dragon tyrant" though.
I've recently re-read Moldvay Basic. There is quite a bit of detail on how to design and stock a dungeon, handle wandering monsters, etc. There is nothing about how you might set up and run a game based on the struggle against a dragon tyrant (or any other sort of tyrant), in which treasure is acquired not by looting it but by being gifted it by mysterious forces (hermits, Elrond, whatever), and the like.
I find that 4e core in turn doesn't support PC's coming into rulership (which many heroic stories support), or the leading of armies, or even the hireing of henchmen.
Henchmen are covered in the DMG2 (companion rules) and Mordenkainen's Magnificant Emporium. There are no rules for it in the PHB.
Rulership and leadership is covered via the Paragon Path and Epic Destiny Rules. You become a leader of armies by taking the Knight Commander paragon path (PHB). You becme a ruler by taking the Eternal Sovereign Epic Destiny (MP2?).
How doesn't the selection of one's race, class, alignment, etc. not embed PC's in circumstances of heroic conflict. Yet again this seems more based in campaign/setting than in the rules.
Page 37 of the 4e PHB tells me this about dwarves:
More so than most other races, dwarves seek guidance and protection from the gods. They look to the divine for strength, hope, and inspiration, or they seek to propitiate cruel or destructive gods. Individual dwarves might be impious or openly heretical, but temples and shrines of some sort are found in almost every dwarven community. Dwarves revere Moradin as their creator, but individual dwarves honor those deities who hold sway over their vocations; warriors pray to Bahamut or Kord, architects to Erathis, and merchants to Avandra—or even to Tiamat, if a dwarf is consumed by the dwarven taste for wealth.
Dwarves never forget their enemies, either individuals who have wronged them or entire races of monsters who have done ill to their kind. Dwarves harbor a fierce hatred for orcs, which often inhabit the same mountainous areas that dwarves favor and which wreak periodic devastation on dwarf communities. Dwarves also despise giants and titans, because the dwarf race once labored as the giants’ slaves. They feel a mixture of pity and disgust toward those corrupted dwarves who still have not freed themselves from the giants’ yoke—azers and galeb duhrs among them.
Moldvay Basic doesn't give me this sort of information about what it means, in the fiction, to be a dwarf. It tells me that dwarves are stubborn, practical and love hearty meals and strong drink. This is a bit of colour, but it does not locate dwarves in any sort of mythic or heroic conflict.
I just wonder if this is the type of heroic fiction the majority of D&D players were or are interested in recreating.
I don't know how many are, but clearly some are. It's the whole premise of Dragonlance, for example.