I don't believe that DDN should continue to play the "Make the game X because I already have Y." game.
We all know the game is Dungeons AND Dragons, and while editions prior may have leaned more towards Dungeons or Dragons, I feel that this constant see-sawing, pendulum-swinging action(also with kung-fu grip!) is what has largely given rise to the great divisions between editions and players.
IMO: DDN should aim for both styles of play, but as you mention with Dark Sun, playing Dragons may require someone to start at above-average.
I just ran a one-shot encounter with a friend of mine last night, he needs to kill a young red dragon for some PRC in 3.5, we skipped the grid and just threw some dice at each other, and though he game close, the dragon ripped him to shreds at the last moment.
This was both Dungeons AND Dragons. Combat was quick(the whole thing took us maybe 5 rounds and 10 minutes), but it was epic. He crit with a weapon of impact and tore off almost 70% of the dragon's health in round, but as he got low on health he tried to run away. A potion of fire resistence saved him from the dragon's breath weapon, but once he stopped to try and pummel the dragon the dragon got it's full-attack and crit with a tail attack, squashing my poor friend.
It was fun, it was exciting, it was fast, and most of all, it was epic....
but... he was level 8.
I think D&D is a big game, and it has plenty of room for Dungeons and Dragons, however, IMO: in the early levels, level 1-6ish the expectation should be mostly limited to Dungeon play, while the later game, and indeed most of the game beyond 8th level, should revolve around Dragons play. Epic battles, world-altering events, monstrous creatures, the things that truly define a fantastical world and the people within it. That doesn't mean Dragons play can't be fast, as per my example, epic battles can often be very quick and easy to run.
I don't think that DDN should strive for Dungeons at the expense of Dragons, nor Dragons at the expense of Dungeons. Because alone, neither Dungeons nor Dragons individually are games I want to play.