A very thorough and apt analysis of the modules faults. On the converse, I'd love to see folks take a stab at giving a summary of what/how they would change the module.
Theme: Each of the prior modules succeeds by picking a theme and doing it well. Q1 has no theme. Now, we could give it lots of different themes and there is no one 'right' choice, but it should have one. If the space ship isn't to be abandoned, than lets run with Lolth as the evil incarnation of industry and technology theme. It could work, and it fits well enough to Lolth as a spider, albiet we'd need to change the Drow - but they badly need a makeover anyway. Lolth subtly protrayed as greedy evil CEO is a bit too anachronistic for my taste, but at least it is a theme. Alternately, you could dump the space ship and run with Lolth as the evil incarnation of cunning, deception, and trickery with layers and layers of webs of illusion that have to be pierced before reaching her inner sanctum. Or maybe both. But some thought and care should be given to actually having a coherent theme.
Scope: The original portrays the outer planes on too small a scale. Borrowing a page from how Gygax portayed the underdark, I'd make the first part of the journey to the citidel have a more wilderness exploration feel. Only, here the wilderness is miles long 50' wide spider threads with the occasional asteroid trapped within. There is an infinite universe of these threads suspended in an infinitely deep pit which is catching things as they fall on their infinitely long journey down the abyss. Whole societies of unfortunate souls try to eke out an existance suspended in the intersections of several threads. Spiders from the size of the garden variety to monterous collossal 1000' across things that less notice of you than you would an ant abound, each spinning webs anchored to the webs of the greater. In the distance, 80 or so miles away from your starting point, is Lolth's mountainous fortress. The whole point of such a scale is: "What the heck are you doing here? You are trying to kill a goddess? Are you insane or what?" If such thoughts aren't entering your mind, you are muddling around a mundane dungeon.
Foes: The set peices against the Vrock is one of the better ones in the module, and shows better what a party at 14th level should be facing rather than 66 gnolls (wrong demon lord!) or 33 bugbears or 20 ogres or (wait for it) 10 trolls. By no means should this be a place dressed like a mundane dungeon, but rather should reflect positively on Lolth's status as a sovereign and a deity. Lolth herself should not be a passive foe sitting back waiting for the PC's, but some one who has tormented them actively every step of the way since the PC's invaded her realm. Whenever any foe comes to interpose itself, they should see her hand at work. Every difficulty and obstacle, from the thread they are walking on snapping to the violent thunderstorm that threatens to blow them into the infinite pits or other entrapment, should be Lolth trying to kill them. She should - perhaps literally - haunt the background of the abyssmal plane as a giant, shadowy and fearsome foe who is clearly personally offended by the PC's and taking personal interest in them. Give them players something to hate, and a reason to really relish their ultimate triumph.
Climax: As long as you are going to have alternate planes you are going to have to chase Lolth into to utlimately kill her, then you need either a Q2 describing such a chase (including likely Lolth as the literal CEO in an office at the top of a skyscraper in a modern earth like world, imagine D&D meets the Matrix) or to include the details of such a chase in the module. Don't just throw out these ideas, "Oh yeah, instead of an empty room for you to populate, there is an entire universe for you. Have fun with that."
UPDATE: Ok, after a bit of thought. Here is what I would do. "Queen of the Demonweb Pits" would be broken up, like the G and D series before it, into three modules: Q1: The Demonweb Pits, Q2: Palace of the Demon Queen, and Q3: The Queen of the Endless Nets
Q1: Arriving in the abyss, the players see the scene I've described above of the incomprehensibly vast and infinite web. Fortunately, the can also see Lolth's Palace, a mountain sized fortress city of towers and smoke stacks bound together by webs in the distance. A wilderness jouney ensues, with the PC's having to deal with the spirits of dead Drow (possibly including some vengeful ones they slew in life), the hazards of an alien plane, and the Meddling of the Queen of this place in a 400' high wraithlike form.
Q2: Arriving at the gates of Lolth's Fortress, the PC's must make their way through Lolth's slave pits, where the souls of dead drow labor in endless drudgery to maintain her huge smoke belching machines. There they learn that Lolth's kingdom is enternally at war with itself, in a vast never ending and ultimately hopeless slave revolt. Profitting from the confusion and backstabbing, the PC's enter the heart of the fortress and make their way through Lolth's minions in an increasingly magi-tech world where the webs are made of wires, living souls, and illusion. Finally, reaching the throne of Lolth, they must fight through Lolth's last gaurds and illusions. Lolth however, now fearing the PC's rather than despising them, in desparation jumps through a portal to an alien world.
Q3: Now pursuing the desparate spider Queen through her strongholds across space and time, the PC's enter a series of 6 mini-modules each with a different theme. In each mini-module, Lolth has hidden herself. The PC's must find and identify and unmask the real Lolth with in the environment that they find her. Finally, at the end of the sixth interlude, the PC's awake to find that they have may never left Lolth's throne room after all, but are now bound to webs strung between pillars and are only now awaking from coma and bondage. With no other options left, Lolth turns and fights her pursuers in an Epic battle while the threads that sustain her fortress snap and come unwound, and the Drow she dominated rise up and slay their taskmasters. With Lolth slain, the PC's find themselves dangling from the end of a thread, while Lolth's fortress and all its inhabitants collapse into the Abyss beneath them.