I believe a good adventure should consist just of a villain, his organization, and his plan. Maybe even dungeon maps, but those are usually not necessary.
Because I never have just the right party that the adventure is made for, I have to write all the stats for NPCs myself, and select what monsters the party will encounter.
Also, the adventures are never written for my setting, so I need to change the races of NPCs and the species of most monsters.
Treasure is also something that is very easy to do yourself, and any pregenerated treasure is never really going to be matching every GMs campaigns style for how much wealth and magic gear the party should get.
What I really need from an adventure, and what I always only take, is the general outline of the events in which the party gets involved, and who their opposition is and how they are working.