Indeed, The Temple of Elemental Evil shouldn't even be on the players' radar initially. I envision a campaign set in the eastern Kron Hills and western Gnarley Forest. The players, being the agents of Celene, Verbobonc, Furyondy, and/or Veluna, are investigating a rise in banditry and humanoid raiding in the region. Nobody suspects the Temple; it was overthrown years ago, and all that remains of it are ruins. And besides, Y'dey and Otis would surely know if anything was going on on that front.
There would need to be a whole set of fleshed-out villages in the forest, complete with deep-cover agents of the now-resurgent Temple. Why would there just be a moathouse thirty miles southwest of the Temple? Surely that would have been only one of a whole system of outworks. There could be a watchtower to the south, originally to keep an eye on Celene and give the humanoids coming up from the Pomarj a place to aim for. And a fort on Imredys Run, now used by river pirates. And an opening in a mine in the central Kron Hills, leading to the Underoerth, whence come those drow that have been seen around the region. All of the former Temple fortifications don't have to have a direct tie-in, but some of them can.
And while Hommlet was described in detail, Nulb was left for the DM to flesh out, after a few detailed locales were given. And Sobanwych remains nothing more than a name. But Verbobonc itself is a hive of Temple operatives, keeping an eye on the forces of Good to the north. I'd like to see a treatment of the whole city, or at least the features that the module says the DM should make sure are described. Could there be evil gnomes in Namburil in the Temple's employ? And what about Corustraith? In later years it's the center of activity for the Rangers of the Gnarley, but in CY 576 it could be a lot more open. They all want full treatments, describing both the agents of the Temple slowly recruiting bandits and humanoids, and the agents of the surrounding Good powers working to keep an eye out.
Maybe they're both playing both sides against one another, and hoping to make out with the best deal. That shifty-looking guy in the tavern? Yes, he's not what he seems, but he's not working for the Temple, he's working for Narwell. Lots of factions, lots of intrigue, lots of chances for role-playing and false leads to follow up. Lovely.
The campaign would unfold in typical Gygaxian fashion. The PCs would be sent to take out a particular bandit group, which would lead to another, and another, with the layers of the onion leading to the Temple agents in various villages and locales, leaving the PCs to figure out that there are powers behind the bandits, and then powers behind those powers, leading to the Temple. They spiral in on the Temple over time, rather than that being the obvious goal from the outset.
So rather than the "you arrive at a seemingly peaceful village near the evil Temple", it becomes "you're rooting out some ordinary-seeming bandits, and learn that there's a shadowy figure behind them, and then there's some sort of weird cult behind him, and now it looks like that cult is tied to the Temple, but they also have their tentacles into the government of Verbobonc who hired you in the first place, so just who can you trust?"
I find that a lot more satisfying. Turn the whole thing from two villages and two dungeons into a whole wilderness campaign with multi-layered political intrigues, bandit fighting, clearing out former(?) Temple locales, eventually culminating in the assault on the Temple itself.
And of course once you get there, you realize that the Temple itself is riven with factions, and there's a whole shrine to the Elder Elemental God that nobody, not even the evil priests in the Temple, expects to be there, and loosing Zuggtmoy could strengthen or even loose the EEG inadvertently (and won't Lolth be pleased if THAT happens*)...
Just a snapshot into what my little "fix the ToEE" project is morphing into. It's huge, and sprawling, and wonderfully complex. No idea what will ever become of it.
* Something just occurred to me. Falrinth, the high-level magic-user on level 3 of the dungeon, is obviously an agent of Lolth in the Temple (he's got a small shrine to her in his quarters). He also has the Golden Orb of Death, which could be used to free Zuggtmoy, but seems to be sitting on it for some reason. What if he had instructions from Lolth not to use it or remove it from the premises, not only because she's happy to see Zuggtmoy helpless, but also because she intuits that doing so might lead to the Elder Elemental God (with whom she has a great rivalry and history) being freed from his prison on a distant star? Ohhh, I like that.