Wyatt Barnett in his Sitepoint article, "I've Never Met a Boxed CMS I Like" makes some very valid points about content management systems straight out of the box. Take note that he isn't just talking about commercial products but also open source systems. His first complaint about "boxed" CMS:
The first issue is that the very nature of a CMS is not easily boxable, without creating an application that tries to do everything for everyone and fails at doing most things particularly well. The tasks required for content management are generic, but every organization has a far different focus when it comes to how that content should be managed and how it thinks about that content. I have lost days of meetings trying to help subject matter experts understand that an article, according to this system, is really a page. Trying to make a generic application to handle this for all comers is a very, very tricky prospect.
Sadly, his post doesn't really offer a solution. I assume building your own CMS is the only alternative to the boxed version. But I have to ask, who really has the time? I think there are some obvious reasons you see so many capable software developers are using open source software such as Wordpress, TYPO3, e107, Alfresco, and Drupal for their Web presence.
I am of the opinion that using a boxed CMS sure beats building your own CMS. I would rather worry more about pushing content than having everything perfect in a custom made CMS. That my two cents worth...