Yeah; I'd say that D1-3 (and Q1 for that matter) are more setting material than adventure. Really, PCs could have any kind of goal by the time they penetrate to the depths of the earth: Slaying Eclavdra, driving the drow into so much internecine confusion that they abandon their plans to manipulate events in the Lands Above, or possibly defeating Lolth. GDQ1-7 makes the adventure goal explicit: In order to rescue Sterich, the PCs *must* penetrate the Demonweb and defeat Lolth.
I tend to think that the adventure series works best without Q1: That is, that the climax of the adventure should be an epic battle against the Eilserv-Tormtor fashion, or better still a grand manipulation that gets the drow factions to turn on each other and the other houses to exterminate the Eilservs/Tormtors as heretics. Leave Lolth out of it; she's a god, she's not to be messed with, and there's no real reason to throw an extraplanar jaunt into it. I've actually run it two different ways: The first time, as a battle against Eclavdra (including a mission to free two enslaved NPCs), and the second, as a return to the Vault of the Drow and an expedition to the Demonweb Pits in order to halt a Lolth-sponsored invasion of the PCs' realm.
As for D2: I think it (and D3) are designed so that the PCs can walk through them without fighting anything. After all, this isn't 3e; adventure design in those days wasn't built around the idea that PCs would need to face x level-appropriate encounters in order to be ready for the next stage. If the PCs are intending to accomplish a goal that's beyond their means, level-wise, before they get to the Shrine of the Kuo-Toa, then they either need some foes thrown in their path to garner them XP, or the DM just needs to give them XP for successfully bypassing challenges.