If you understand the principles behind website templates you will immediately see the huge benefits to WordPress template systems. Basically it is designed to hookup automated template ideas to a system via which a client who knows nothing about anything can access your site (behind password protection obviously) and update and manage the website that you leave him.
I'd like to give you an example: I recently wrote an article outlining several ways to get out of a writing slump. As I was writing that article, I came up with about 7 or so ideas for getting your brain out of a creative rut with your articles, including some article template ideas and some writing productivity techniques. I submitted the article, and then thought__ "Each of those ideas for getting out of a writing slump needs to be elaborated on and explained further. I can do a new article for each idea." And so I did__so far I've bounced 4 or 5 articles off of that first article, and I have even more ideas that I've gotten from that first article that I haven't written about yet.