In D&D, modules are like the Ikea furniture of adventures. They're out-of-the-box campaigns you can run your party through, and they generally do a pretty good job. But sometimes theres a few screws missing, and even if there isn't, it's not quite as rewarding as building something from scratch. However, there's nothing that says you can't toss out parts of the instructions and assemble the module however you want—by adding some homebrew. (Note: do not throw out the instructions for your Ikea furniture, unless you want your Morabo to come out lookin' like an Ektorp).