Top ten reasons why Drupal and Joomla! suck:

1. They are way too easy to install and configure.
2. They are excellent at managing content.
3. One does not have to give anyone their credit card information to download them.
4. They have way too many 3rd party extensions, especially Joomla.
5. They have communities that are way too large and, on the whole, much too friendly and helpful.
6. They are easy to write templates/theme for (although some may give Joomla! the edge here).
7. They have forums where users can ask and answer questions.
8. They have semi-decent documentation
9. They have created a service industry around them, e.g., selling templates, themes and extensions, building web sites, providing ongoing operations and maintenance support, etc.
10. They have provided shining examples of the benefits of open source software development.