Wordpress makes sense for the same reasons (good) frameworks make sense: somebody's already written the code to provide blogging/publishing functionality, and they're experts at it. Plus, it is extensible w/ plugins and has numerous options for themes.

If the site needs something that's not part of the Wordpress core and there's no plugin, write some PHP and make it.

Granted, it's not quite as hardcore and writing a custom app, but why reinvent the wheel?