For some content types and properties, default height of the textarea field in Drupal is 5 rows. That's too low in itself but if you install TinyMCE, it just plain squishes:

Obviously, you can resize the field but why should the default be messed-up and scare users away? Following is a quick-fix for the problem.

Open includes/ file in your Drupal installation and in the beginning of the theme_textarea(\$element) method, insert:

 if ( $element['#rows'] < 10 ) {