My two Euro cent: I think that developing a unique site in WordPress is substantially more effort than doing without a content management system. I find it's intellectually more demanding - because without a CMS, the extent of the files that we'd have to worry about for a three page website would be something like this:
HTML files - index.html, about.html, contact.html,
CSS stylesheets - reset.css, 960.css, style.css,
JavaScript - jquery-1.8.2.min.js, script.js.
in addition, probably, to a number of image files.
If I'm doing something solely for my own use, and I'm not anticipating the project growing to encompass more than a few pages, then I've no reason not to take this approach. Except for that creating all of these files from scratch involves a lot of duplication, as has already been noted. With that in mind, I tend to use a customized version of HTML5 Boilerplate (http://html5boilerplate.com/) - which puts the bare bones structure of the site in place.
If I'm developing a site for someone else, the likelihood is that they're going to want to be able to make changes to the content themselves without having to alter the source code of the site, which pretty much means that using some sort of CMS is essential.
At the moment, I'm experimenting with Bones - http://themble.com/bones/ - a WordPress Theme for Developers based on HTML5 Boilerplate. You pretty much have to use a CSS preprocessor such as LESS or SASS to use it, and it takes a while to get your head around it, but it's a lot less mind boggling than trying to write a theme from scratch. I'd be very much interested to hear what other people's approaches are. 
