Web site templates are also used for generating massive number of web pages by means of a schematic layout. Template based web designing is best when one requires building a site that has lots of pages and navigation link. It is ideal to use a web template if the site needs to be updated from time to time.
The first reason would be because hiring a web developer or designer is going to consume far more time than getting website templates. Think about it, you have to explain to the web developer exactly what you want. You have to go over it with them again and again and again. You will have to monitor what is being created and make adjustments during the project. Once the project is finished it is probably going to be behind schedule, and adjustments will need to be made that might cost you more money and more time.