Here's what I think a published campaign adventure should have:
1) Motivation for the characters (and their players) to go on the adventure.
2) A story/plot/background that the GM can convey to the players - and the logical means of sharing that information naturally within the adventure.
3) Clear goals, which are more or less achievable (by sword, spell, or wits) by the character level range indicated by the adventure.
4) A unified theme building up to a satisfying climactic resolution
5) Consistency and logical story/world building.
6) A compelling villain, antagonist ("conflict" to use a literary term)
Of course you need maps, enemies, encounters, treasures, traps, etc. But without the things I mentioned above, you have an adventure site, not a campaign. There are additional items I prefer to see in my adventures, but I think without the above, you're not going to have a successful campaign without adding lots of additional work.