I think in the BLT analogy...rpg's in general are sandwiches, while specific roleplaying games are specific sandwiches. To say I just wanted a very good sandwich is to say I just wanted a good rpg. This could, depending on one's tastes include Exalted, WoD, D&D 4e, Runequest, Warhammer FRPG, True20 or Pathfinder.
The problem with Generic Food Metaphors is that they're so hard to evaluate! How do I know that RPGs as a whole are not like tasty light lunches, and D&D is a sandwich, and only a particular way of playing D&D (a type I don't like, given I'm a vegetarian) is a BLT?
Now if you want D&D in particular, then you are buying it because you expect (from past experiences) certain things from said game.
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D&D 4e feels incomplete because it has removed many of the previous editions tropes...both fluff and mechanical...and replaced them with less.
Which is interesting. Because I am looking at 4e and seeing the first version of D&D I can imagine running and playing in a serious campaign since 1st ed and Moldvay/Cook. Now I'm not one of those who thinks that 4e is retro - for a mainstream RPG its design is pretty cutting edge - but I do think that it evokes the tropes of classic D&D: the goblins and kobolds look right to me (on paper, at least - our game won't start until a couple of existing campaigns come to an end over the next month or so), the PCs are exciting and the mechanics seem evocative of a fantasy world without being either backwards or tedious.
At the moment I'm working on a conversion of B10 - Night's Dark Terror, an old 2-4 level module from the Menzer era of D&D. This seems very well suited to 4e - plenty of minion-heavy combats, skill challenges (of course they weren't called that in the original module, but I think that they can fairly easily be reconfigured), points of light, ancient empires, haunted places of darkness (ie Shadowfell) and faerie (ie Feywild), etc.
For me one of the least inspiring things about 3E was the general trend in WoTC adventures towards dungeon-heavy, story-light grinds. IMO the Demonweb Pits and Greyhawk hardbacks really exemplify this, as do many of the 3E-era online and Dungeon adventures. (When I say that these are story-light I don't mean that they lack backstory for the benefit of the GM - I mean that they are virtually railroads, which offer little chance for the players to meaningfully interact with or shape the story). I feel that these adventures have the burdensome weight of the old 1st ed dungeons (C-series, S-series, etc) without the trade-off of the comparative lightness-of-touch of the 1st ed mechanics.
Given that 4e seems very apt to facilitate a less grinding approach to play than 3E (with quests, skill challenges, and other complex reward mechanics, interacting with complex and multi-layered action currencies) I'm hoping that 4e adventures will reflect that (classic D&D modules that I'd put into this category are B10, X2, and the interlude-y aspects of D1, D2 and D3, but not the Shrine or the Fane in the latter two modules). On a quick skim of the Dungeon modules to date Heathen looks promising to me, Sleeper so-so and Rescue very dungeon-grindish.