Install/Upgrade System
VaultWiki is now a huge product with many updates. Installing the product file uses a bunch of server resources at once, which could cause install errors.
vBulletin uses a step-by-step install system, where you have to click "Next Step" to move on. This allows the install process to balance its strain on the server and be less prone to errors. Also an install script is nicer looking than a product file.