Hommlet's a really cool place. There are a few things that I find quite humorous about it (no, I don't think I need to know that the elderly farmer at the modest farmhouse has 172 ep, 51 gp, and 20 pp hidden underneath some rusty nails in a keg in the back shed), but overall I appreciate it as a well-fleshed-out village that provides enough background for the PCs to find it worth their time. Hommlet is a great place to be from and go back to.
What it doesn't do, however, is provide clear means for the PCs to move on. Oh, sure, there are the traders, who are obviously up to something, and there are rumblings in the background about how things are getting more dangerous on the roads, but there's not a clear and present direction. Effectively, the PCs are required to go door to door, asking, "Excuse me, but have you seen an adventure?"
This isn't a problem, necessarily - it certainly preserves player agency, and the premise is that they did come looking for adventure - but I feel like more could be done to represent the various factions, and indeed should be. Hommlet is a place, not an adventure.
In the game I plan to run, the traders are still agents of the Temple, and they're still skeevy and conniving. However, they know of the existence of Lareth, and furthermore they dislike him and want him gone. Lareth represents a budding foe that, at the best, represents a rival faction in the temple vying for dominance. So, once the party makes it clear to the townsfolk that they've arrived on the scene, the traders will seek them out and, attempting a private conference, try to engage them to root out and destroy Lareth. They're still wretches - they'll shortchange the PCs if possible, give them cheap equipment, and so on - and they'll still betray the PCs at the end, engaging a squad of brigands and assassins to waylay them on the road at some later time. However, overall they do want the PCs to succeed, at least in clearing out the moathouse.
Lareth, for his part, has no love for the traders, and cares little for the Temple of Elemental Evil. Lolth would find such a structure and following useful, but usurping Iuz and controlling the minions of Zuggtmoy is quite difficult, especially with no more than a toehold in the area. When the PCs come after Lareth, his inclination will be toward parley, especially if it's clear that the traders sent them. In fact, he'll offer thanks for clearing out the bandits above (who were drawing unwanted attention to the abandoned moathouse, after all) and even engage the PCs as a patron if they so desire. He will betray both the presence of the Temple and the traders' involvement with it, and encourage the PCs to clear out the place if they can.
Of course, Lareth is still jealous, not wanting anyone else to supplant him in the eyes of his spider-queen. If the PCs become too successful - say, they manage to disrupt two of the four elements in the Temple - Lareth will quietly hire an assassination party to, ah, quell their enthusiasm.
All that aside, it's still possible for the PCs to go to the moathouse without the influence of the traders. Both the captain of the guard and Elmo will talk about the place, as will the publican. This just provides some extra incentive and another real choice about its resolution. It provides the PCs a plausible way to work for evil, as well, since evil puts on numerous faces.