Why bother using a premade mobile website template? Why not do it yourself? You don't want to sit down and learn it. You'll have to learn how to code HTML, learn how to make graphics in Photoshop, learn how to use FTP and upload the images into the proper places. That's just for starters. What file is the main page for the cellular site (default). Depending on the server, it could be default.asp, index.asp, index.php, or main.aspx. What happens if you click on a link, and it goes nowhere. How do you fix that? Why is the image not appearing? These are many questions you will need to answer to have a properly-functioning website. A lot of these headaches are solved with choosing instead to use a handsfree website template.
The advantage of using a website template is a professional designer has already created dozens or hundreds of templates for clients, and knows already what works best and what people end up being happy with. Other advantages of using a template are:

Considerably reduced cost from thousands to around $60

The design is ready to go, already coded, just needs content and copy put in

HTML bugs are already worked out, no recoding and redesign

Designs can be modified: change the color, replace an image - with very little effort

Depending on the design, it can be used with a content manage system like Joomla, Zen Cart, Wordpress, Mambo, etc

You know exactly what the website looks like right now as opposed to starting a design from scratch: you have no idea what the designer is going to produce, if you will like it, and you'll have to pay for revisions you don't like (wasting money)