'Absolutely'. As the author notes usability and ease of use matter. They are the number one feature to the end user. There is one more and this is more for developers, wordpress database is made up of ten tables! Within these ten tables they have managed to slot in a multi-blog feature. This compares to over 50 for Drupal for example. As a developer, I can get into the internals of WP and make modifications fairly easily - in most cases there are plugins to assist as a starting point.
Overall WP has managed to carve a sexy niche in the hearts of users and developers even if the code is not so beautiful and sexy, not to mention the language!